Question

For women aged​ 18-24, systolic blood pressures are normally distributed with a mean of 114.8 mm Hg and a standard deviation of 13.1 mm Hg. If 23 women aged​ 18-24 are randomly​ selected, find the probability that their mean systolic blood pressure is between 119 and 122 mm Hg. Round to four decimal places.

Answer 1

Answer:

0.0579 is the probability that mean systolic blood pressure is between 119 and 122 mm Hg for the sample.

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 114.8 mm Hg

Standard Deviation, σ = 13.1 mm Hg

Sample size = 23

We are given that the distribution of systolic blood pressures is a bell shaped distribution that is a normal distribution.

Formula:

$z_{score} = \displaystyle\frac{x-\mu}{\sigma}$

Standard error due to sampling:

$\displaystyle\frac{\sigma}{\sqrt{n}} = \frac{13.1}{\sqrt{23}} = 2.731$

P(blood pressure is between 119 and 122 mm Hg)

$P(119 \leq x \leq 122) = P(\displaystyle\frac{119 - 114.8}{2.731} \leq z \leq \displaystyle\frac{122-114.8}{2.731}) = P(1.537 \leq z \leq 2.636)\\\\= P(z \leq 2.636) - P(z < 1.537)\\= 0.9958 - 0.9379 = 0.0579= 5.79\%$

$P(119 \leq x \leq 122) = 5.79\%$

0.0579 is the probability that mean systolic blood pressure is between 119 and 122 mm Hg for the sample.