Question

What is the probability that a normal random variable will take a value that is less than 1.05 standard deviations above its mean? In other words, what is P(Z < 1.05)?

- .8531
- .1468
- .9332
- .0668

What is the probability that a normal random variable will take a value that is between 1.5 standard deviations below the mean and 2.5 standard deviations above the mean? In other words, what is P(-1.5 < Z < 2.5)?

- .9938
- .0668
- .9270
- .0730

What is the probability that a normal random variable will take a value that is more than 2.55 standard deviations above its mean? In other words, what is P(Z > 2.55)?

- .9945
- .9946
- .0055
- .0054

Answer #1

1. A continuous random variable is normally distributed. The
probability that a value in the distribution is greater than 47 is
0.4004. Find the probability that a value in the distribution is
less than 47.
2. A continuous random variable is normally distributed. The
probability that a value in the distribution is less than 125 is
0.5569. Find the probability that a value in the distribution is
greater than 125.
3. A random variable is normally distributed with mean 89.7...

There is a 90% probability that a Normally distributed random
variable be less than:
1) 0.90 standard deviations above its mean
2)1.28 standard deviations above its mean
3) 1.50 standard deviations above its mean
4)1.64 standard deviations above its mean
5)2.33 standard deviations above its mean

What is the probability of a normal variable being lower than
5.2 standard deviations below its mean?
Do you need to know the mean and standard deviation?
2. What is the probability of a normal variable being within 1.2
standard deviations of its mean?
Do you need to know the mean and standard deviation?

a. If X is a normal random variable with mean 10, and if the
probability that X is less than 11.54 is .72 then what is the
standard deviation of X?
1.75
3.50
4.20
12.25
b. If the standard deviation of a population is 36 and we take a
sample of size 9, then the standard error (the standard deviation
of the sample mean) is
12.00
3.00
108.00
4.00
c. According to the empirical rule, in a normal distribution
about...

let
z be a random variable with a standard normal distrubtion. find the
indicated probability (round your answer to four decimal places).
a) P(z ≥ -1.53)=
b) P(z ≤ -2.04)=
c) P(-2.00 ≤ z ≤ 1.05)=
d) P(0 ≤ z ≤ 0.50)=

1. If random variable X follows a Normal probability
distribution, a negative Z score means
(a) The value of X is negative
(b) The value of X is less than the mean
(c) The value of X is greater than the mean
(d) the correlation between X and Z is negative
(e) none of the above.
2. Which of the following statements is not true about the
Normal Curve
(a) The total area under the Normal Curve is 1.
(b)...

If you select a random z-score from the normal distribution,
what is the probability that you will get a value greater than 2.5?
Put differently, P(z>1.5) = ? (Answer to 3 digits after the
decimal.) ?

2.)Assume random variable Z follows standard normal
distribution; find the value of the following probabilities.
P(-1<Z<1)
3.)Assume random variable Z follows standard normal
distribution; find the value of the following probabilities.
P(0<Z<1)
4.)Assume random variable Z follows standard normal
distribution; find the value of the following probabilities.
P(Z>2)
5.)The natural log of growth of yucca tree is approximately
normally distributed with mean of 0.053 mm and standard deviation
0.03mm. Determine the probability that a yucca tree has growth less
than...

A: Let z be a random variable with a standard normal
distribution. Find the indicated probability. (Round your answer to
four decimal places.)
P(z ≤ 1.11) =
B: Let z be a random variable with a standard normal
distribution. Find the indicated probability. (Round your answer to
four decimal places.)
P(z ≥ −1.24) =
C: Let z be a random variable with a standard normal
distribution. Find the indicated probability. (Round your answer to
four decimal places.)
P(−1.78 ≤ z...

Let z be a random variable with a standard normal distribution.
Find the indicated probability. (Round your answer to four decimal
places.) P(z ? ?0.25)
Let z be a random variable with a standard normal distribution.
Find the indicated probability. (Round your answer to four decimal
places.) P(z ? 1.24)
Let z be a random variable with a standard normal distribution.
Find the indicated probability. (Enter your answer to four decimal
places.) P(?2.20 ? z ? 1.08)

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