homework 3

Refer to the accompanying data set and use the 30 screw lengths to construct a frequency distribution. Begin with a lower class limit of 0.720 ​in, and use a class width of 0.010 in. The screws were labeled as having a length of 3/4 in. Does the frequency distribution appear to be consistent with the​ label? Why or why​ not? Complete the frequency distribution below. Length​ (in) Frequency 0.720- Does the frequency distribution appear to be consistent with the​ label? A. ​Yes, because the screw lengths are no more than .03 in off the labeled size. B. ​Yes, because the frequencies are greatest in the classes closest to the labeled size. Your answer is correct.C. ​No, because the screw lengths are off by as much as 0.03 in. D. ​No, because the class frequencies are not consistent.

Length​ (in) Frequency 0.720-0.729 1 0.730-0.739 3 0.740-0.749 12 0.750-0.759 12 0.760-0.769 2

A​ _______ helps us understand the nature of the distribution of a data set.

frequency distribution

In a​ _______ distribution, the frequency of a class is replaced with a proportion or percent.

relative frequency

Class width is found by​ _______. A. subtracting the lower limit of one class from the upper limit of that same class B. subtracting a lower class limit from the next consecutive lower class limit C. subtracting the smallest value in the data set from the largest value in the data set D. adding the lower class limit to the upper class limit and dividing by two

subtracting a lower class limit from the next consecutive lower class limit

Identify the class​ width, class​ midpoints, and class boundaries for the given frequency distribution. white blood cell count of males - frequency 4.0-5.9 8 6.0-7.9 15 8.0-9.9 11 10.0-11.9 5 12.0-13.9 1 what is the class width? what are the class midpoints? what are the class boundaries?

2 4.95, 6.95, 8.95, 10.95, 12.95 3.95, 5.95, 7.95, 9.95, 11.95, 13.95

Construct the cumulative frequency distribution for the given data. Age (years) of Best Actress Frequency when award was won 20-29 26 30-39 35 40-49 13 50-59 3 60-69 7 70-79 1 80-89 1 Age​ (years) of Best Actress Cumulative Frequency when award was won Less than 30 x Less than 40 x Less than 50 x Less than 60 x Less than 70 Less than 80 Less than 90

26 61 74 77 84 85 86

Daily Low Temperature (°F) Frequency 40-42 1 43-45 3 46-48 5 49-51 11 52-54 7 55-57 7 58-60 1 what is the class width? what are the class midpoints? what are the class boundaries?

3 41 44 47 50 53 56 59 39.5, 42.5, 45.5, 48.5, 51.5, 54.5, 57.5, 60.5

After constructing a relative frequency distribution summarizing IQ scores of college​ students, what should be the sum of the relative​ frequencies? A. If percentages are​ used, the sum should be​ 0%. If proportions are​ used, the sum should be 0. B. If percentages are​ used, the sum should be​ 100%. If proportions are​ used, the sum should be 100. C. If percentages are​ used, the sum should be​ 100%. If proportions are​ used, the sum should be 1. D. If percentages are​ used, the sum should be​ 1%. If proportions are​ used, the sum should be 100.

If percentages are​ used, the sum should be​ 100%. If proportions are​ used, the sum should be 1.

Refer to the accompanying data set and use the 25 home voltage measurements to construct a frequency distribution with five classes. Begin with a lower class limit of 125.4 ​volts, and use a class width of 0.2 volt. Does the result appear to have a normal​ distribution? Why or why​ not? Complete the frequency distribution below. Voltage​ (volts) Frequency 125.4 - Does the result appear to have a normal​ distribution? Why or why​ not? A. No, because the frequencies are roughly equal across the voltagevoltage classes.classes. B. Yes, because the frequencies start low, reach a maximum, then become low again, and are roughly symmetricand are roughly symmetric about the maximum frequency.about the maximum frequency. C. ​No, because the frequencies are not equal across the voltage classes. D. ​No, because the frequencies are randomly distributed. E. Yes, because the frequencies are roughly equal across the voltage classes.

Voltage​ (volts) Frequency 125.4-125.5 5 125.6-125.7 5 125.8-125.9 4 126-126.1 6 126.2-126.3 5 A

The data represents the body mass index​ (BMI) values for 20 females. Construct a frequency distribution beginning with a lower class limit of 15.0 and use a class width of 6.0. Does the frequency distribution appear to be roughly a normal​ distribution? Body Mass Index Frequency 15.0-20.9 21.0-26.9 27.0-32.9 33.0-38.9 39.0-44.9 Does the frequency distribution appear to be roughly a normal​ distribution? A. Yes, all of the requirements are met. B. No, although the distribution is approximately​ symmetric, the frequencies do not start​ low, then increase to some maximum​ frequency, then decrease. C. No, although the frequencies start​ low, increase to some​ maximum, then​ decrease, the distribution is not symmetric. D. ​No, the distribution is not symmetric and the frequencies do not start off low.

frequency: 3, 8, 5, 3, 1 C

​_______ are sample values that lie very far away from the majority of the other sample values.

outliers