Question

The blood pressure of a person changes throughout the day. Suppose the systolic blood pressure of a person is measured 36 times over several days and the standard deviation of these measurements for the person is known to be σ = 3.6 mmHg. Let μ be the true average blood pressure for that person and let the average of the 36 measurements be 7.1.

Find a upper-bound 90% confidence interval for μ. One can be 90% confident that the true average blood pressure μ for that person is at most b.

What is the value of b? Round your answer to the nearest 0.01.

Answer 1

Solution :

Given that,

=7.1

= 3.6

n = 36

At 90% confidence level the z is ,

  = 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

Z_/2 = Z_0.05 = 1.645

Margin of error = E = Z_/2* ( /n)

= 1.645 * ( 3.6/ 36)

= 0.987

At 90% upper confidence interval is,

+ E

7.1+0.987

8.087

answer 8.087