If amount of utility bill is normally distributed with a mean of $105 and a standard deviation of $20. What percentage of your bills would you expect to be between $85 and $125?

68% of your bills between $85 and $125

Step-by-step explanation:

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

Mean = $105

Standard deviation = $20

What percentage of your bills would you expect to be between $85 and $125?

85 = 105 - 20

125 = 105 + 20

Within one standard deviation of the mean, so by the Empirical Rule, 68% of your bills between $85 and $125

a. she will receive a refund of $278.

step-by-step explanation:

37/3

step-by-step explanation:

step 1: simplify both sides of the equation.

7x+8(x+

1

4

)=3(6x−9)−8

7x+(8)(x)+(8)(

1

4

)=(3)(6x)+(3)(−9)+−8(distribute)

7x+8x+2=18x+−27+−8

(7x+8x)+(2)=(18x)+(−27+−8)(combine like terms)

15x+2=18x+−35

15x+2=18x−35

tep 2: subtract 18x from both sides.

15x+2−18x=18x−35−18x

−3x+2=−35

step 3: subtract 2 from both sides.

−3x+2−2=−35−2

−3x=−37

step 4: divide both sides by -3.

−3x

−3

=

−37

−3

x=

37

3