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hoa [83]
3 years ago
9

Jill sold half of her comic books then bought 16 more, she now has 36. With how many did she begin with? Break it down please

Mathematics
1 answer:
marusya05 [52]3 years ago
4 0
A: 40

Let’s do this problem backwards.


TOTAL BOOKS RN: 36

1)
“Jill... then bought 16 more...”

36 - 16 = 20

After subtracting that amount, we would end up with half of the books Jill DID NOT sell.

2)
2 • 20 = 40

At this point, we multiplied amount of books she had after she sold half of her comic books by the reciprocal of 1/2

And now you have your answer!
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Consider the following data set. The data were actually collected in pairs, and each row represents a pair.
Anna11 [10]

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Step-by-step explanation:

Hello!

a.

Using the data sets you have to analyze them as if they are two independent samples.

The hypotheses are:

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H₁: μ₁≠μ₂

α: 0.05

Assuming that both data sets are from a normal distribution and both population variances, although unknown, are equal, the statistic to use is:

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The p-value for the two-tailed test is:

P(t_{18}≤-0.875) + P(t_{18}≥0.875)= P(t_{18}≤-0.875) + (1 - P(t_{18}≤0.875))= 0.1965 + ( 1 - 0.8035)= 0.393

Since there is no significant level I determined it at 5%, comparing it to the p-value, the hypothesis test is not significant. Meaning that the difference between the population means of both groups is equal to zero.

b.

Considering the given data as a paired sample, you have to determine the variable difference to conduct the test:

Xd: the difference between X₁ and X₂

Before the sample mean and sample standard deviation you have to calculate the difference between the observations of group 1 and group 2. (2nd attachment)

Mean X[bar]d= -0.83

Standard deviation Sd= 1.28

The hypotheses for the paired sample test are:

H₀: μd=0

H₁: μd≠0

α: 0.05

t= \frac{X[bar]d-Mud}{\frac{Sd}{\sqrt{n} } } ~~t_{n-1}

t_{H_0}= \frac{-0.83-0}{\frac{1.28}{ \sqrt{10} }} = -2.05

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Comparing the p-value with the significance level, the hypothesis test is not significant. Meaning that the population mean of the difference between group 1 and group 2 is equal to cero. There is no difference between the two groups.

c.

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The main difference is that in "a" you compared two different samples but in "b" you compared two dependent samples when analyzing paired data the "effect of the individual" is removed from the equation.

I hope this helps!

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