Question

Systolic blood pressure in 18-year-old women has a bell-shaped distribution with a mean of 120mmHg and a standard deviation of 12mmHg. What percent of 18-year-old women have systolic blood pressure between 96mmHg and 144mmHg?

select one
a) Approximately 95%
b) approximately 75%
c) approximately 99.7%
d) approximately 68%

Answer 1

We have,

Mean () = 120 mmHg

Standard deviation () = 12 mmHg

Given distribution is bell shaped.

We have given two values 96 and 144.

96 = 120 - 24

= 120 - 2(12)

= - 2

Also

144 = 120 + 24

= 120 + 2(12)

= + 2

According to Empirical Rule, about 68% of data lie within one standard deviation, about 95% data lie within two standard deviations and about 99.7% data lie within three standard deviation from mean.

As calculated above, data values between 96 and 144 lie within two standard deviation from the mean.

Therefore according to Empirical Rule approximately 95% of data values lie between 96 and 144.

Therefore approximately 95% of 18 year old women have systolic blood pressure between 96 mmHg and 144 mmHg.

Therefore the correct option is option A.