Question

7. A student wants to estimate the mean score of all college students for a particular exam. First use the range rule of thumb to make a rough estimate of the standard deviation of those scores. Possible scores range from 800 to 1400. Use technology and the estimated standard deviation to determine the sample size corresponding to a 90​%

confidence level and a margin of error of 100 points. What​ isn't quite right with this​ exercise?

Answer 1

Solution :

7)

Given that,

Maximum = 1400

Minimum = 800

Range = maximum - minimum = 1400 - 800 = 600

Using Range rule of thumb

Standard deviation = Range / 4 = 600 / 4 = 150

Population standard deviation = = 150

Margin of error = E = 100

Z_/2 = 1.645

sample size = n = [Z_/2* / E] ²

n = [1.645 * 150 / 100]²

n = 7

Sample size = n = 7

Sample size is fairly small number .