Hello,
I have this problem:
Q: "Suppose the rockwell hardness is normally distributed with mean 70 and standard deviation 3 on a continuous scale."
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?
I'm unsure of how to work this part of the problem. I assume 95% means that it is 2 StDev's of the mean, but i'm not real sure how to apply that.
I think it's asking what c is if: P(70 - c < Z < 70 + c). But i'm not sure how I would solve C from that. (I'm actually really confused about what's going on in this topic...)
edit: After looking at it some more I think one way might be: [(70 - c) - 70]/3 = -2 to solve for c using the formula Z = (X-70)/3 where X is 70 - c. This gives me c = 6. Is this possible?
I have this problem:
Q: "Suppose the rockwell hardness is normally distributed with mean 70 and standard deviation 3 on a continuous scale."
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?
I'm unsure of how to work this part of the problem. I assume 95% means that it is 2 StDev's of the mean, but i'm not real sure how to apply that.
I think it's asking what c is if: P(70 - c < Z < 70 + c). But i'm not sure how I would solve C from that. (I'm actually really confused about what's going on in this topic...)
edit: After looking at it some more I think one way might be: [(70 - c) - 70]/3 = -2 to solve for c using the formula Z = (X-70)/3 where X is 70 - c. This gives me c = 6. Is this possible?