STAT QUIZ 3

Suppose a coin is tossed three times. Let X denote the total number of tails obtained in the three tosses. What are the possible values of the random variable X?

0, 1, 2, 3

What probability value would be needed to complete the following probability distribution? x -2 -1 0 1 2 P(x) 0.16 0.23 0.12 0.31

0.18

Property crime rates (per 100,000 residents) for the 50 states and the District of Columbia have a mean of 3377.2 and a standard deviation of 847.4. Assuming the distribution of property crime rates is normal, what percentage of the states has property crime rates between 2360 and 4055?

0.67

Scores on the verbal section of the SAT have a mean of 500 and a standard deviation of 100. Scores are approximately normally distributed. What proportion of SAT scores are higher than 450?

0.6915

The area that lies to the right of -1.82

0.9656

The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.32 inches?

2.28%

Find the z-score having area 0.09 to its left under the standard normal curve.

-1.34

Find the z-score for which the area under the standard normal curve to its left is 0.96

1.75

The number of cartoons watched by Mrs. Kelly's first grade class on Saturday morning is shown below. x 0 1 2 3 4 5 P(x)0.15 0.20 0.30 0.10 0.20 0.05 What is the mean distribution of the data given above?

2.15

The annual precipitation for one city is normally distributed with a mean of 390 inches and a standard deviation of 3.2 inches. Fill in the blanks. In 95% of the years, the precipitation in this city is between ___ and ___ inches.

383.6, 396.4

Scores on the verbal section of the SAT have a mean of 500 and a standard deviation of 100. Scores are approximately normally distributed. If someone scored at the 90th percentile, what is their SAT score?

628

The lifetimes of light bulbs of a particular type are normally distributed with a mean of 360 hours and a standard deviation of 5 hours. What percentage of the bulbs have lifetimes that lie within 1 standard deviation of the mean?

68%

The systolic blood pressure of 18-year-old women is normally distributed with a mean of 120mmHg and a standard deviation of 12 mmHg. What percentage of 18-year-old women have asystolic blood pressure that lies within 3 standard deviations of the mean?

99.7%

The following distribution is not a probability distribution because x -5 -4 -3 -2 -1 P(x) 0.08 0.23 0.44 0.12 0.24

The probability values do not add to 1

Which of the following is not true about the standard normal distribution?

The area under the standard normal curve to the left of z= 0 is negative

I pledge that this assignment is the sole work of me. I did not get any help from anyone except some reference to class materials.

True