Question 1076105: 1.)Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 42; σ = 14
P(50 ≤ x ≤ 70) =
2.)Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 14.2; σ = 3.1
P(8 ≤ x ≤ 12) =
3.) Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 24; σ = 3.4
P(x ≥ 30) =
4.)Assume that x has a normal distribution with the specified mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)
μ = 111; σ = 15
P(x ≥ 90) =
*Please tell me how you figure out these two:
5.)Find z such that 6.6% of the standard normal curve lies to the left of z. (Round your answer to two decimal places.)
z =
6.)Find z such that 9.2% of the standard normal curve lies to the right of z. (Round your answer to two decimal places.)
z =
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Go to the z-table where the shaded area is on the right. Look for .0920, and that is +1.33 or very close to the intersection of the +1.3 and the .03 at the top.
For 6.6%, you find 1.505. But this is -1.505 (interpolate between the two values) because you want the area to the left and the normal distribution is symmetrical. You can do the area to the right and just change the sign.
For mean of 42 with sd 14
z=(number-mean)/sd=(50-42)/14=0.571
z(70)=(70-42)/14=2
The probability of z between those two values is 0.2612.
The others are done the same way.
Calculator it is 2nd VARS 2 and put the two z values if it is in between, separated by a comma, then hit enter.
If it is to the left, use -6, whatever the z value is. -6 is essentially 0 in the z-distribution. If it is to the right, use number, 6, since 6 will take care of everything to the right. Some use 9999, but that is more than you need.
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