Boy's brickshas determined that a brick measuring 5 inches long has a z score of +1 and a brick measuring 5.75 inches long has a z-score of 2
what is the mean length of the bricks produced at bob's bricks?
4.00 inches
4.25 inches
4.75 inches
5.25 inches

The mean length of the bricks is 4.25 inches ⇒ 2nd answer

Step-by-step explanation:

* Lets explain how to solve the problem

- z-score = , where x is the score,

  M is the mean and α is the standard deviation

- A brick measuring 5 inches long has a z score of + 1

- A brick measuring 5.75 inches long has a z-score of 2

* Lets use the rule of z-score to find the mean length of the bricks

∵ x = 5 and z-score = + 1

∴

- By using cross multiplication

∴ α = 5 - M ⇒ (1)

∵ x = 5.75 and z-score = 2

∴

- By using cross multiplication

∴ 2α = 5.75 - M ⇒ (2)

- Substitute α in equation (2) by equation (1)

∴ 2(5 - M) = 5.75 - M

∴ 10 - 2M = 5.75 - M

Subtract 5.75 from both sides and add 2M to both sides

∴ 10 - 5.75 = 2M - M

∴ 4.25 = M

∵ M represents the mean length of the bricks

∴ The mean length of the bricks is 4.25 inches

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation:

a precentage of 6th graders. the population is all 6th graders. let me know if i'm wrong, i hope this ! : )

step-by-step explanation: