Assume that blood pressure readings are normally distributed with a mean of 123 and a standard deviation of 9.6. If 144 people are randomly selected, find the probability that their mean blood pressure will be less than 125.
a) 0.9938
b) 0.9998
c) 0.0062
d) 0.8615

The probability is 0.9938

Step-by-step explanation:

In this question, we are asked to calculate the probability that the mean blood pressure readings of a group of people is less than a certain reading.

To calculate this, we use the z score.

Mathematically;

z = (mean - value)/(standard deviation/√N)

From the question, we can identify that the mean is 125, the value is 123 , the standard deviation is 9.6 and N ( total population is 144)

Let’s plug these values;

z = (125-123)/(9.6/√144) = 2.5

Now we proceed to calculate the probability with a s score less than 2.5 using statistical tables

P(z<2.5) = 0.9938