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Measure up Clarence measures the diameter of each tennis ball in a bag with a standard ruler. Unfortunately, he uses the ruler incorrectly so that each of his measurements is 0.2inchtoo large. Clarence鈥檚 data had a mean of 3.2inchesand a standard deviation of 0.1inch (Recall that 1in.=2.54cm)

a. Find the mean of the corrected measurements in centimeters.

b. Calculate the standard deviation of the corrected measurements in centimeters.

Short Answer

Expert verified

Part (a) Mean of the corrected measurements is 7.62cm

Part (b) Standard deviation of the corrected measurements is 0.254cm

Step by step solution

01

Part (a) Step 1: Given information and Explanation

1in.=2.54cm

Mean,

xin=3.2inches

Standard deviation,

SDin=0.1inches

Every data value must be multiplied by 2.54in order to convert from inches to centimeters.

We must reduce the measurement (or data value) by 0.2inches for corrected measurements since the measurement was 0.2inches too large.

Because the center of the measurements is represented by the mean.

When every data value is multiplied by 2.54then the center of the distribution is also multiplied by 2.54

Similarly,

When every data value is decreased by 0.2inchesthen the center of the distribution is also decreased by 0.2inches

Then

The new mean of the corrected measurements in centimeters is the mean of the uncorrected measurements in inches decreased by 0.2inches

multiplied by 2.54

New mean,

xcm=(xin-0.2).2.54=(3.20.2)2.54=(3)2.54=7.62cm

Thus,

The mean of the corrected measurements in centimeters is 7.62cm

02

Part (b) Step 1: Calculation

Standard deviation, SDin.=0.1inches

Every data value must be multiplied by 2.54 in order to convert from inches to centimeters. We must reduce the measurement (or data value) by 0.2 inches for corrected measurements since the measurement was 0.2 inches too large. Because the standard deviation is a measure of variance.

When each data value is multiplied by 2.54, the measurement variability is also multiplied by 2.54 And the variability of the measurements will not be changed if each data value is reduced by 0.2inches

Then

The corrected measurement's new standard deviation in centimeters equals the uncorrected measurement's standard deviation multiplied by 2.54

New standard deviation,

SDcm.=2.54(SDin.)=2.54(0.1)=0.254cm

Thus,

The standard deviation of the corrected measurements in centimeters is 0.254cm

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