The rockwell hardness of a metal is determined by

impressing a hardened point into the surface of the

metal and then measuring the depth of penetration of the

point. suppose the rockwell hardness of a particular

alloy is normally distributed with mean 70 and standard

deviation 3. (rockwell hardness is measured on a continuous

scale.)

a. if a specimen is acceptable only if its hardness is

between 67 and 75, what is the probability that a randomly

chosen specimen has an acceptable hardness?

b. if the acceptable range of hardness is (70-c, 70+c) ,

for what value of c would 95% of all specimens have

acceptable hardness?

the answer is simply just 6n add the two together as they have an n

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

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step-by-step explanation:

b. y = 4x - 2

step-by-step explanation:

to find a parallel equation to an equation, make sure both equations have the same slope but different y-intercepts.

y = 4x + 1

4 = slope

1 = y-intercept

y = 4x - 2

4 = slope

-2 = y-intercept

they both have the same slope but different y-intercepts, so, b. is the correct answer.

and to check your work, you can graph both equations. : )

hi im bob : l

step-by-step explanation: