Question

True or False: A race car driver tested his car for time from 0 to 60 mph, and in 20 tests obtained an average of 4.85 seconds with a standard deviation of 1.47 seconds. A 95% confidence interval for the 0 to 60 time is 4.52 seconds to 5.18 seconds.

Answer 1

Answer:

False

Step-by-step explanation:

given that a race car driver tested his car for time from 0 to 60 mph, and in 20 tests obtained an average of 4.85 seconds with a standard deviation of 1.47 seconds.

Sample size n = 20

since population standard deviation is not known, we can use t critical value for finding out the confidence interval

df=19

t critical = 2.045

Margin of error = $2.045*\frac{s}{\sqrt{n} } \\=2.045*\frac{1.47}{\sqrt{20} } \\=0.6722$

conidence interval = Mean±Margin of error

= $(4.85-0.6722, 4.85+0.6722)\\= (4.1778, 5.5222)$

The given confidence interval is (4.52, 5.18)

Hence the statement is false.