Question

The commute time to work in the U.S. Has a bell shaped distribution with a population mean of 24.4 minutes and a population standard deviation of 6.5 minutes. What proportion of the population has a commute time: a) between 11.4 minutes and 37.4 minutes? (1 pt) b) less than 11.4 minutes? (1 pt) c) greater than 37.4 minutes? (1 pt)

Answer 1

Answer:

1. 0.9544

2. 0.0228

3. 0.0228

Step-by-step explanation:

The computation is shown below;

As we know that

At Normal distribution

$P(X < A) = P(Z < \frac{(A - mean)}{standard deviation})$

As per the question, the data provided is as follows

Mean = 24.4 minutes

Standard deviation = 6.5 minutes

Based on the above information

P(11.4 < X < 37.4) = P(X < 37.4) - P(X < 11.4)

= P(Z < (37.4 - 24.4) ÷ 6.5) - P(Z < (11.4 - 24.4) ÷ 6.5)

= P(Z < 2) - P(Z < -2)

= 0.9772 - 0.0228

= 0.9544

2. P(X < 11.4) = 0.0228

3. P(X ≥ 37.4) = 1 - P(X < 37.4)

= 1 - 0.9772

= 0.0228