Question

Data was collected on reaction time of both hands for an experiment. 14 out of 27 students had a faster reaction time with their right hand than with their left hand. Using this information, we wish to construct a confidence interval for the proportion of all WCU students that have a faster reaction time with their right hand than with their left hand.

Calculate the lower boundary of a 99% confidence interval.

Give your answer as a decimal rounded to 3 places after the decimal.

Answer 1

0.3902

Explanation:

The question meets the criteria for the calculation of the confidence interval of a one sample proportion ;

Sample size, n = 27

Number of students with faster reaction time = 14

Phat = x / n = 14 / 27 = 0.6296

The confidence interval is calculated thus :

C. I = Phat ± Zcritical * √[p(1 - p)/n]

Zcritical at 99% = 2.576

C. I = 0.6296 ± 2.576 * √[0.6296(0.3704)/27]

C.I = 0.6296 ± 0.2394042

The lower boundary of C.I = 0.6296 - 0.2394042

Lower boundary = 0.3902