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3 years ago

13

Rainforest data:

1 answer:

scoundrel [369]3 years ago

4 0

Answer:

x is = 11.7 μ=7

z11.7 ≈ 1.3

next two is A and B

Step-by-step explanation:

These are correct 100%

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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

2 years ago

The number of chairs increased by 7 <br><br> A.cx7<br> B.c+7<br> C.c/7<br> D.c-7

miss Akunina [59]

B.c+7
hope that helps!

7 0

3 years ago

Write the ratio as a fraction in simplest form 25 to 45

brilliants [131]

Answer:

5/9

Step-by-step explanation:

3 0

3 years ago

Question 1 x - 2.5 = -3

MAVERICK [17]

Answer:

x = -.5

Step-by-step explanation:

x - 2.5 = -3

Add 2.5 to each side

x - 2.5+2.5 = -3+2.5

x = -.5

8 0

2 years ago

The square of a number, x, is 16 less than eight times the number. What is the number? Type the correct answer in the box. Use n

liraira [26]

Given :

The square of a number, x, is 16 less than eight times the number.

To Find :

The value of x .

Solution :

The mathematical equation with all given data is :

$x^2=8x-16\\\\x^2-8x+16=0\\\\x^2-4x-4x+16=0\\\\x(x-4)-4(x-4)=0\\\\(x-4)^2=0\\\\x=4$

Therefore , the value of x is 4 .

Hence , this is the required solution .

3 0

2 years ago