Question

A World Health Organization study (the MONICA project) of health in various countries reported that in Canada, systolic blood pressure readings have a mean of 119 and a standard deviation of 17. A reading above 136 is considered to be high blood pressure.

(a) How many standard deviations away from the mean is a blood pressure reading of 136?
(b) If systolic blood pressure in Canada is approximately normal, find the proportion of Canadians that suffer from high blood pressure.
(c) If systolic blood pressure in Canada is approximately normal, what is the probability that a randomly selected Canadian has a systolic blood pressures in the range from 101 to 136.

Answer 1

Mean = = 119

Standard deviation = = 17

a)

So 1 standard deviation away from the mean is a blood pressure reading of 136.

b) In this part, we have to find P(X > 136)

For finding this probability we have to find a z score.

That is we have to find P(Z > 1)

P(Z > 1) = 1 - P(Z < 1) = 1 - 0.8413 = 0.1587 ( Using z table)

c) In this part, we have to find the probability that a randomly selected Canadian has a systolic blood pressure in the range from 101 to 136.

That is we have to find the P( 101 < X < 136)

For finding this probability we have to find a z score.

That is we have to find P( - 1.06 < Z < 1)

P( - 1.06 < Z < 1) = P(Z < 1) - P(Z < - 1.06) = 0.8413 - 0.1448 = 0.6965