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The amount of time all students in a very large undergraduate statistics course take to complete an examination is distributed c

Anestetic [448]

Answer:

a) The mean is $\mu = 60$

b) The standard deviation is $\sigma = 9$

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

The probability a student selected at random takes at least 55.50 minutes to complete the examination equals 0.6915.

This means that when X = 55.5, Z has a pvalue of 1 - 0.6915 = 0.3085. This means that when $X = 55.5, Z = -0.5$

So

$Z = \frac{X - \mu}{\sigma}$

$-0.5 = \frac{55.5 - \mu}{\sigma}$

$-0.5\sigma = 55.5 - \mu$

$\mu = 55.5 + 0.5\sigma$

The probability a student selected at random takes no more than 71.52 minutes to complete the examination equals 0.8997.

This means that when X = 71.52, Z has a pvalue of 0.8997. This means that when $X = 71.52, Z = 1.28$

So

$Z = \frac{X - \mu}{\sigma}$

$1.28 = \frac{71.52 - \mu}{\sigma}$

$1.28\sigma = 71.52 - \mu$

$\mu = 71.52 - 1.28\sigma$

Since we also have that $\mu = 55.5 + 0.5\sigma$

$55.5 + 0.5\sigma = 71.52 - 1.28\sigma$

$1.78\sigma = 71.52 - 55.5$

$\sigma = \frac{(71.52 - 55.5)}{1.78}$

$\sigma = 9$

$\mu = 55.5 + 0.5\sigma = 55.5 + 0.5*9 = 55.5 + 4.5 = 60$

Question

The mean is $\mu = 60$

The standard deviation is $\sigma = 9$

6 0

3 years ago

Can someone please help me

PtichkaEL [24]

Answer:

The size is 37.5 degrees

Step-by-step explanation:

The total angle in the triangle is 180

Since the other two angles are congruent. it means that they are equal

Let us call each of the angles x

Mathematically,

x + x + 105 = 180

2x = 180-105

2x = 75

x = 75/2

x = 37.5

7 0

3 years ago

PLEASE HELP!! (and show steps if u can)

Flauer [41]

Answer:

slope: -1

Step-by-step explanation:

Complete y2 - y1 over x2 - x1 with your given points.

-3 - (-1) = -2

_____ ___

2 - 0 = 2

= ⁻²⁄₂ = -1 Simplify to lowest term

3 0

3 years ago

MATH

ale4655 [162]

Answer:

the answer is 3

Step-by-step explanation:

in the number 66 there are "2" circles in them and so the answer we get 2

in the number 99 there are "2" circles and so the answer there is 2

in the number 888 there are "6" circles so the answer is 6

in the number 00 there are "2" circles that's the answer

in the number 7777 there are no circles so the answer is 0

we keep on going like that......

in the number 2876 there are 3 circles 2 in the number 8 and 1 in the number 6

hope this helped :D

7 0

3 years ago

Which number is the least prime number: 0, 1, 2, or 3?

Alinara [238K]

1 is the least prime number

5 0

3 years ago

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