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liq [111]
3 years ago
13

1-part B 2- part B 4- 5- Please someone help I don’t understand

Mathematics
1 answer:
pickupchik [31]3 years ago
5 0
The answer to the questions

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Simplify the expression: 42 + 8 ÷ 2.
igor_vitrenko [27]
Your final answer is 25 
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3 years ago
if in the study of the lifetime of 60-watt light bulbs it was desired to have a margin of error no larger than 6 hours with 99%
Dahasolnce [82]

The question is incomplete! Complete question along with answer and step by step explanation is provided below.

Question:

The lifetime (in hours) of a 60-watt light bulb is a random variable that has a Normal distribution with σ = 30 hours. A random sample of 25 bulbs put on test produced a sample mean lifetime of = 1038 hours.

If in the study of the lifetime of 60-watt light bulbs it was desired to have a margin of error no larger than 6 hours with 99% confidence, how many randomly selected 60-watt light bulbs should be tested to achieve this result?

Given Information:

standard deviation = σ = 30 hours

confidence level = 99%

Margin of error = 6 hours

Required Information:

sample size = n = ?

Answer:

sample size = n ≈ 165

Step-by-step explanation:

We know that margin of error is given by

Margin of error = z*(σ/√n)

Where z is the corresponding confidence level score, σ is the standard deviation and n is the sample size

√n = z*σ/Margin of error

squaring both sides

n = (z*σ/Margin of error)²

For 99% confidence level the z-score is 2.576

n = (2.576*30/6)²

n = 164.73

since number of bulbs cannot be in fraction so rounding off yields

n ≈ 165

Therefore, a sample size of 165 bulbs is needed to ensure a margin of error not greater than 6 hours.

3 0
3 years ago
2968 Divided. By. 56. What. Is the answer to this problem please show your work
Sladkaya [172]

Answer:

53

Step-by-step explanation:

i had to use this old method (pic related).

8 0
3 years ago
Plsssssssssssss help
Rudiy27
The picture is too blurry for me even when I try zooming in on it
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2 years ago
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Brent is saving for a computer that is $840. He will also need to pay a 6% sales tax. What is the total cost of the computer aft
Kobotan [32]

Answer:

$890.4

Step-by-step explanation:

840 + .06(840)

840 + 50.4

890.4

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3 years ago
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