The distribution of speeds along a certain stretch of highway has an mean of 76 mph and a standard deviation of 7 mph.
What percentage of cars would be traveling slower than 55 mph?

0.13%

Step-by-step explanation:

Given that :

Mean = 76mph

Standard deviation = 7 mph

Percentage of cars traveling slower than 55mph

Obtain the Zscore :

X = 55mph

Zscore = (X - mean) / standard deviation

Zscore = (55 - 76) / 7

Zscore = - 3

P(Z < - 3)

From the z table :

P(Z < - 3) = 0.0013

Hence, percentage of cars traveling slower than 55mph is (0.0013 * 100%) = 0.13%

from the figure we get,

the x axis shows   the months and,

the y-axis shows the number of satisfied customer.

each line or each cell in upward direction (y-axis) shows 500.

the appropriate scale for the y - axis is: -

a = 2000 customers

b = 4000 customers

c = 6000 customers

d = 8000 customers

e = 10000 customers

f = 12000 customers

g = 14000 customers