Lakeisha spent $4.57 on color and black-and-white copies for her project. She made 7 more black-and-white copies than color copies. How many color copies did she make?

Step-by-step explanation:

Here is the complete question

Lakeisha spent $4.57 on color and black-and-white copies for her project. She made 7 more black-and-white copies than color copies. How much color did she make?

Key: color- $0.44 per page

black-and-white: 7 cents per page

Let the amount of color be x

Let the amount of black and white be y

If amount per page of color is $0.44, then x color will cost 0.44x

If amount per page of white and black cost $0.07, then y white and black will cost $0.07y

Since She made 7 more black-and-white copies than color copies, this means:

y = x+7 1

If the total spent on black and white is $4.57 then;

0.44x+0.07y = 4.57 2

Substitute 1 into 2

0.44x+0.07(x+7) = 4.57

0.44x + 0.07x+0.49 = 4.57

0.51x = 4.57-0.49

0.51x = 4.08

x = 4.08/0.51

x = 8

This means that I made 8 color copies

21, 144, 12

Step-by-step explanation:

Given that a sample of 30 distance scores measured in yards has a mean of 7, a variance of 16, and a standard deviation of 4.

Let X be the distance in yard.

i.e. each entry of x is multiplied by 3.

New mean variance std devition would be

E(3x) =

Var (3x) =

Std dev (3x) =

Thus we find mean and std devition get multiplied by 3, variance is multiplied by 9