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Dovator [93]
3 years ago
8

A sample of size 20 from a normal distribution has sample mean 3.5 and sample variance 14.75. Find 90% confidence intervals for

the variance and standard deviation of the distribution.
Mathematics
1 answer:
aleksley [76]3 years ago
5 0

Answer:

Variance =9.2983, 27.6927

Standard deviation = 3.0493, 5.2624

Step-by-step explanation:

n = 20

S = 14.75

X² = chisquare

N-1 = degree of freedom

Alpha = 0.1

Alpha/2 = 0.1/2 = 0.05

1-0.1/2 = 0.95

Using statistics table

X² 19,0.05 = 30.14

X² 19, 0.95 = 10.12

A. 19(14.75)/30.14 , 19(14 75)/10.12

= 9.2983, 27.6927 for the variance of the population

B. Standard deviation = square root of variance

= √9.2983, √27.6927

= 3.0493, 5.2624

Please use attachment for better understanding

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60,40,35,45,39

Put in order from least to greatest

35, 39, 40, 45, 60


Range = Max - Min

Range = 60 - 35

Range = 25


Answer

D) 25

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3 years ago
Use back-substitution to solve the system of linear equations.
ludmilkaskok [199]

Step-by-step explanation:

x - y + 5z = 29

y + 2z = 4

z = 7

since z = 7 we can use this value in second equation

y + 2×7 = 4 and y = -10

now we know the value of y we can solve the first equation

x -(-10) + 5×7 = 29

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-8, 1, 10...<br> n<br> What is a formula for the ninth term of the given sequence
krek1111 [17]

9514 1404 393

Answer:

  a9 = -8 +9(9 -1)

Step-by-step explanation:

The given sequence has a common difference of 1-(-8) = 10-1 = 9, and a first term of -8. The formula for the n-th term of such an arithmetic sequence is ...

  an = a1 +d(n -1) . . . . . first term a1, common difference d

For the parameter of this sequence, a1=-8 and d=9, the n-th term is ...

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6 0
3 years ago
The officer stepped off 20 paces from E to G. If his pace is 2 1/2 feet long. How wide was the river?
Sergeeva-Olga [200]

Answer:

The wide of river is 50\ ft

Step-by-step explanation:

In this problem we know that

Triangles DEG and DEF are congruent by ASA (Angle-Side-Angle) Congruence

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8 0
3 years ago
2.
iren [92.7K]

Answer:

  • Part A: The price of fuel A is decreasing by 12% per month.

  • Part B: Fuel A recorded a greater percentage change in price over the previous month.

Explanation:

<u>Part A:</u>

The function     f(x)=2.27(0.88)^x     calculates the price of fuel A each month by multiplying the price of the month before by 0.88.

Month       price, f(x)

1                 2.27 (0.88) = 1.9976 ≈ 2.00

2                2.27(0.88)² = 1.59808 ≈ 1.60

3                2.27(0.88)³ = 1.46063 ≈ 1.46

Then, the price of fuel A is decreasing.

The percentage per month is (1 - 0.88) × 100 = 12%, i.e. the price decreasing by 12% per month.

<u>Part B.</u>

<u>Table:</u>

m       price, g(m)

1          3.44

2         3.30

3          3.17

4         3.04

To find if the function decreases with a constant ration divide each pair con consecutive prices:

  • ratio = 3.30 / 3. 44 = 0.959 ≈ 0.96
  • ratio = 3.17 / 3.30 = 0.960 ≈ 0.96
  • ratio = 3.04 / 3.17 = 0.959 ≈ 0.96

Thus, the price of fuel B is decreasing by (1 - 0.96) × 100 =4%.

Hence, the fuel A recorded a greater percentage change in price over the previous month.

5 0
3 years ago
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