Phlebotomy Laboratory Mathematics Review

What does 2.2 pounds (lb) equal in the metric system? a. 1 kg b. 44 g c. 100 g d. 454 kg

Answer: a WHY: One kilogram equals 2.2 lb (Table AppB-3). This is a conversion factor that should be memorized. A helpful hint might be to remember that weight in kilograms is approximately half (divide by 2) the number given in pounds. However, it is important to remember that this number will always be slightly higher than an actual calculation.

The basic unit of mass in the metric system is the: a. gram. b. liter. c. meter. d. ounce.

Answer: a WHY: The basic unit of mass in the metric system is the gram (Table AppB-3).

A blood culture bottle containing 45 mL of media requires a 1:10 dilution of specimen. How much blood should be added? a. 4 mL b. 5 mL c. 8 mL d. 10 mL

Answer: b WHY: A blood culture dilution of 1:10 means there is 1 mL of blood and 9 mL of media for every 10 mL of blood culture specimen. Forty-five milliliters of media is five times the original proportion of nine milliliters. To maintain the same 1:10 dilution, you must also have five times the original 1 mL proportion of blood. That means you will need to add 5 mL blood to the 45 mL media.

Body temperature in centigrade degrees is: a. 98.6. b. 37.0. c. 25.0. d. 32.0.

Answer: b WHY: Body temperature in centigrade is 37°. To calculate body temperature in centigrade when given a Fahrenheit reading, subtract 32 from the Fahrenheit temperature and multiply by 5/9. Note: A healthcare worker should memorize the centigrade body temperature value along with a few other centigrade temperatures that are common when working in healthcare (Fig. AppB-2).

One teaspoon is approximately: a. 1 mL. b. 5 mL. c. 10 mL. d. 15 mL.

Answer: b WHY: By using an English-Metric conversion chart (Table AppB-2), you can find the right answer, or you may choose to memorize certain common conversions, such as 1 tsp = 5 Ml.

If room temperature is 77ºF, what is the temperature in centigrade? a. 20 b. 25 c. 32 d. 37

Answer: b WHY: Centigrade and Celsius are equal. To convert 77° Fahrenheit (F) temperature to centigrade (C) or Celsius (C), subtract 32 from the Fahrenheit value and multiply the result by 5/9. Formula: C=5/9 (F-32) Solution: F-32=77-32=45 5/9(45)=5/9x45/1 5/9x45/1=225/9 225/9=25degreesC Room temperature in Celsius or centigrade is 25°C. Healthcare workers should memorize this commonly referenced centigrade temperature (Fig. AppB-2).

Your text says that factor VIII is the antihemophilic factor. What common Arabic number is this factor? a. 4 b. 8 c. 13 d. 23

Answer: b WHY: Coagulation factors such as the antihemophilic factor are written in Roman numerals. In Roman numerals, letters equal numbers. The Roman numeral V equals 5, and the Roman numeral I equals 1. When numerals of the same value follow in sequence, their values are added. When a numeral is followed by one or more numerals of a lower value, the values are added. Therefore: VIII = 5 + 1 + 1 + 1 = 5 + 3 = 8

A specimen must be transported at body temperature, plus or minus 5° Fahrenheit. Which of the following temperature readings is within that range? a. 25°C b. 35°C c. 37°F d. 90°F

Answer: b WHY: Fahrenheit body temperature is 98.6° (Fig. AppB-2). Once we add and subtract 5, we know that we are looking for a temperature that is between 93.6°F and 103.6°F. This eliminates 37°F and 90°F. 25°C (Celsius or centigrade) is the same as 77°F. (See answer 6.) The remaining choice is 35°C. To verify that this is the correct answer, convert 35°C to Fahrenheit temperature: Formula: F = 9/5 C + 32 Solution: (9/5 × 35) + 32 = 63 + 32 = 95°F 35°C is the correct answer because it is the same as 95°F, which meets the transportation temperature requirement.

The basic unit of volume in the metric system is the: a. gram. b. liter. c. meter. d. ounce.

Answer: b WHY: The basic unit of volume in the metric system is the liter (L), as shown in Table AppB-3 (Metric-English Equivalents). It is easier to remember that the liter is the basic metric unit of volume than to remember other metric measurements, because the soft drink industry in the United States has converted much of their packaging to metric measurements, and we see advertisements for liters of soft drinks all the time.

Your requisition says that a specimen is to be drawn at 1530. What time would that be in 12-hour time? a. 1:30 AM b. 3:30 PM c. 5:30 AM d. 7:30 PM

Answer: b WHY: To change 24-hour time to 12-hour time, subtract 1200 from any time after 1300. 1530 in 24-hour time less 1200 is 330, which written in 12-hour time format with the colon is 3:30 PM. A clock showing standard and 24-hour (military) time is shown in Fig. AppB-1.

200 µL is equal to: a. 2 mL. b. 0.2 mL. c. 0.02 mL. d. 0.002 mL.

Answer: b WHY: When converting small units to larger units, the decimal point moves to the left the number of spaces determined by subtracting the exponent of the smaller unit from the exponent of the larger unit. A milliliter (mL) is one-thousandth of a liter (L), or 10−3 liters. A microliter (μL) is one-millionth of a liter, or 10−6 liters. Microliters are smaller than milliliters. Therefore, subtract −6 (μL exponent) from −3 (mL exponent). The result is 3, which means the decimal point moves three places to the left. Solution: −3 −(−6) = −3 + 6 = 3 200.0 = 0.2 mL

To prepare 100 mL of a 1:10 dilution of bleach, add: a. 1 mL water to 100 mL bleach. b. 1 mL bleach to 99 mL water. c. 10 mL bleach to 90 mL water. d. 10 mL water to 100 mL bleach.

Answer: c WHY: A 1:10 dilution of bleach means there is 1 mL of bleach and 9 mL of water for every 10 mL of solution. One hundred milliliters of a 1:10 dilution is 10 times the original 10-mL proportion. That means you will also need 10 times the original amount of bleach and water, or 10 mL bleach and 90 mL water.

A patient voids 1200 mL of urine for a creatinine clearance test. How much urine is this? a. Less than a liter b. Less than a quart c. More than a liter d. More than 2 liters

Answer: c WHY: A liter is equal to 1000 mL and a quart is equal to 950 mL; therefore, 1200 mL is 200 mL more than a liter, 250 mL more than a quart, and 800 mL less than 2 liters (Tables AppB-1 and AppB-2). Refer to Questions 15 & 18 for the tables.

If a red blood cell is 8 µm in diameter, what is its size in millimeters? a. 0.8 b. 0.08 c. 0.008 d. 0.0008

Answer: c WHY: A micrometer (μm), or micron, is equal to one-millionth (10−6) of a meter and a millimeter (mm) is equal to one-thousandth (10−3) of a meter, which means you are converting smaller units to larger units (Table AppB-1). When converting small units to larger units the decimal point moves to the left the number of spaces determined by subtracting the exponent of the smaller unit from the exponent of the larger unit. Therefore, subtract −6 (mL exponent) from −3 (mm exponent). The result is 3, which means the decimal point moves three places to the left. Solution: −3 − (−6) = −3 + 6 = 3 008.0 μm = 0.008 mm

In the metric system, a millimeter (mm) is: a. 1/10 meter. b. 1/100 meter. c. 1/1000 meter. d. 1/10,000 meter.

Answer: c WHY: A millimeter (mm) is 1/1000 meter, or 10−3 m (Table AppB-2).

10 cc of blood equals approximately: a. 1.0 mL of blood. b. 5.0 mL of blood. c. 10 mL of blood. d. 20 mL of blood.

Answer: c WHY: For practical purposes, mL and cc are equivalent and the terms are often used interchangeably in a laboratory setting. Both are approximately equal to one-thousandth of a liter. The term milliliter (mL) is used when referring to liquid volume; cubic centimeter (cc) is used when referring to volume of gas. However, syringes that are used to extract liquid volume are often calibrated in cc rather than in mL.

In the metric system the prefix for 1000 is: a. centi-. b. deci-. c. kilo-. d. milli-.

Answer: c WHY: Kilo-, abbreviated "k," means 1000 (Table AppB-1). It can be used with each of the three basic units of measure in the metric system. Example: kilogram (kg) = 1000 grams (g) kiloliter (kL) = 1000 liters (L) kilometer (km) = 1000 meters (m)

In the metric system a meter is a measure of: a. mass. b. density. c. distance. d. volume.

Answer: c WHY: Metric-English conversion equivalent for distance (or length) is the meter (m), as shown in Table AppB-3.

Normal infant blood volume is approximately 100 mL/kg. Calculate the approximate blood volume of a baby who weighs 6 lb. a. 1.2 L b. 2.7 L c. 270 mL d. 600 mL

Answer: c WHY: Normal infant blood volume is approximately 100 mL/kg. If a baby's weight is given in pounds, it must be converted to kilograms by multiplying the pounds by the conversion factor 0.454. Once the weight is established in kilograms, multiply that number by 100, because for every kilogram there are 100 mL of blood. Example: 6lbx0.454=2.7kg(rounded to nearest tenth) 2.7kgx100mL/kg=270mL

A test requires 3 mL serum. The laboratory requires that the amount of blood collected be 250% of the volume of specimen required to perform the test. Which size tube should you use to collect the specimen? a. 4 mL b. 5 mL c. 10 mL d. 15 mL

Answer: c WHY: The laboratory needs 250%, or two and one-half times, the 3 mL required for the test. Two times 3 mL is 6 mL. One-half of 3 mL is 1½ mL (or you can multiply 3 times 2.5). Therefore, you need 7½ mL to do the test. The closest tube choice is 10 mL.

Your paper says that you got 45 of 50 questions correct. What is your grade expressed as a percentage? a. 45% b. 75% c. 90% d. 95%

Answer: c WHY: To calculate a percentage, a number must be converted to parts per 100. First, make the number a fraction. Then multiply the numerator of the fraction by 100, divide by the denominator, and add a percent sign. Solution: 45 of 50=45/50 45/50x100=4500/50 4500 divided by 50=90 Or reduce the fractions first as follows: 45/50 × 100/1 = 45/1 × 2/1 = 45 × 2 = 90%

1:00 PM in 24-hour time is: a. 100. b. 0100. c. 1300. d. 01300.

Answer: c WHY: To convert 12-hour time to 24-hour time, add 1200 to the time (minus the colon) from 1 PM. on. 1:00 without the colon is 100. 100 plus 1200 becomes 1300 (see Fig. AppB-1).

1.2 kg is equal to how many grams? a. 12 b. 120 c. 1200 d. 12,000

Answer: c WHY: When converting large units to smaller units, the decimal point moves to the right. To convert large units to basic units, move the decimal point to the right the value of the exponent of the larger unit. A kilogram (k) is 1000 or 103 grams (Table AppB-2). The exponent is 3, so the decimal point moves three places to the right. Solution: 1.200kg=1200g.

Normal adult blood volume is approximately 70 mL per kilogram. A patient weighs 130 lb. What is the patient's blood volume? a. 1300 mL b. 1.3 L c. 59 kg d. 4.1 L

Answer: d WHY: Normal adult blood volume is approximately 70 mL per kilogram of weight. If the weight is given in pounds, it must be converted to kilograms by multiplying by the conversion factor 0.454 (Table AppB-1). The weight in kilograms is multiplied by 70 because we know that for every kilogram of weight in an adult there is approximately 70 mL of blood. Divide the result by 1000 because adult blood volume is reported in liters and 1 L equals 1000 mL. Example: 130 lb × 0.454 = 59.02 kg 59 kg × 70 mL/kg = 4130 mL 4130/1000 = 4.13 L

How is the number 12 written in Roman numerals? a. IIV b. VII c. IIX d. XII

Answer: d WHY: Roman numerals are written from left to right in decreasing value (except for numerals that are to be subtracted from subsequent numerals). In addition, there can never be more than three of the same numeral in a sequence. To write a number, you should start with the closest base number and add or subtract other numbers until you reach the desired value. The closest base number to 12 is X, which equals 10. Then add one I for every number 1. Therefore: 12 = X + I + I = XII