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Shkiper50 [21]
3 years ago
9

For the past three months, Grace used her cell phone for 43 minutes, 62 minutes, and 57 minutes. How many minutes would she have

to use her cell phone this month for the average usage over the four months to be 55 minutes? Be sure to include units in your answer
Mathematics
1 answer:
Alika [10]3 years ago
6 0

Answer:

Step-by-step explanation:

If they want the average for four months to be 55 minutes, this means that the total of the four months = 55 x 4

Total of four months = 220 minutes

They already told us that the three previous months she used her cellphone for 43 minutes, 62 minutes and 57 minutes.

All you have to do now is subtract everything from the total of the four months.

4th month = 220 - 43 - 62 - 57

= ? Minutes

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The thickness of a plastic film (in mils) on a substrate material is thought to be influenced by the temperature at which the co
statuscvo [17]

Answer:

Step-by-step explanation:

Hello!

The objective is to test if rising the process temperature reduces the thickness of the plastic film that coats a substrate material To do so, two samples of substrates are coated at different temperatures:

Sample 1

X₁: Thickness of the plastic film after the substrate is coated at 125F

n₁=11

X[bar]₁= 101.28

S₁= 5.08

Sample 2

X₂: Thickness of the plastic film after the substrate is coated at 150F

n₂= 13

X[bar]₂= 101.70

S₂= 20.15

Does the data support this claim? Use the P-value approach and assume that the two population standard deviations are not equal.

Now if the higher the heat, the thinner the thickness of the plastic coating, then the average thickness of the coating done at 150F should be less than the average thickness of the coating done at 125F, symbolically: μ₂ < μ₁

Then the hypotheses are:

H₀: μ₂ ≥ μ₁

H₁: μ₂ < μ₁

α:0.05 (there is no α level stated so I've chosen the most common one)

Assuming that both variables have a normal distribution since the population standard deviations are not equal, the statistic to use is the Welch's t-test:

t= \frac{(X[bar]_2-X[bar]_1)-(Mu_1-Mu_2)}{\sqrt{\frac{S^2_1}{n_1} +\frac{S^2_2}{n_2} } } ~~t_w

t_{H_0}= \frac{(101.7-101.28)-0}{\sqrt{\frac{(20.15)^2}{13} +\frac{(5.08)^2}{11} } } = 0.072

This test is one-tailed to the left, meaning that you'll reject the null hypothesis at small values of t. The p-value is also one-tailed and has the same direction as the test. To calculate it you have to first calculate the degrees of freedom of the Welch's t:

Df_w= \frac{(\frac{S^2_1}{n_1} +\frac{S^2_2}{n_2} )^2}{\frac{(\frac{S^2_1}{n_1})^2 }{n_1-1}+\frac{(\frac{S^2_2}{n_2} )^2}{n_2-1}  }

Df_w= \frac{(\frac{5.08^2}{11} +\frac{20.15^2}{13} )^2}{\frac{(\frac{5.08^2}{11})^2 }{10} +\frac{(\frac{20.15^2}{13} )^2}{12} } = 13.78

The distribution is a Student's t with 13 degrees of freedom, then you can calculate the p-value as:

P(t₁₃≤0.072)= 0.4718

Using the p-value approach, the decision rule is:

If the p-value ≤ α, the decision is to reject the null hypothesis.

If the p-value > α, the decision is to not reject the null hypothesis.

The p-value is greater than the significance level, so the decision is to nor reject the null hypothesis.

Using a significance level of 5%, there is no significant evidence to support the claim that the average thickness pf the plastic coat processed at 150F is less than the average thickness pf the plastic coat processed at 125F.

I hope you have a SUPER day!

4 0
3 years ago
Given the equation 4x+5y=20
tester [92]
I hope this helps you

4 0
3 years ago
ASAP!!! ILL GIVE BRAINLIEST !
Alex17521 [72]

Answer:

1) 60

2) 60

3) 119

4) 59

Step-by-step explanation:

All triangle angles add up to 180 degrees. All lines with transversals add to 180 degrees. Use these rules and the measurements given to solve.

3 0
2 years ago
So we are suppose to Factor each expression, But I’m having trouble with that, Can someone help me?
Gre4nikov [31]
42x can be factored into 7(6x), and 49 is square, meaning it can be factored into 7 squared. I believe the factored expression would be 7(6x + 7) because 7 is the greatest common factor between both numbers.

3 0
3 years ago
Billy will earn $8 per hour and work 12 hours per week how much will he earn in one week​
wolverine [178]

Answer:

The answer is simple. If there is $8 an hour and works for 12 hours, just multiply 8 by 12, which is 96. He will earn $96 in a week

Step-by-step explanation:

8 0
3 years ago
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