Question

Suppose it is known that in a certain population the mean systolic blood pressure (SBP) is 120 mmHg and the standard deviation is 10 mmHg. In a random sample of size 40 from this population, what is the probability that this sample will have a mean SBP greater than 124 mmHg?

Answer 1

Solution :

Given that ,

mean = = 120

standard deviation = = 10

n = 40

= 120 and

= / n = 10 / 40

P( > 14) = 1 - P( < 124)

= 1 - P(( - ) / < (124 - 120) / 10 / 40 )

= 1 - P(z < 2.53)

= 1 - 0.9943

= 0.0057

P( >) = 0.0057

Probability = 0.0057