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3 years ago

Mark earned $40 mowing lawns last week. He spent 3/5 of his money on two books. How much did he spend on those two books?

1 answer:

N76 [4]3 years ago

3 0

First, convert 3/5 to a percent by multiplying it by 20/20, getting 60/100, or 60%. Then, find 60% of 40 by multiplying 60 by 40 to get 2,400 and divide it by 100 to get 24, meaning Mark spend $24 on both books. Each of the books cost $12, as 24/2 is 12.

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Consider the following hypothesis test:

Gnom [1K]

Answer:

a. z=3.09. Yes, it can be concluded that the population mean is greater than 50.

b. z=1.24. No, it can not be concluded that the population mean is greater than 50.

c. z=2.22. Yes, it can be concluded that the population mean is greater than 50.

Step-by-step explanation:

We have a hypothesis test for the mean, with the hypothesis:

$H_0: \mu\leq50\\\\H_a:\mu> 50$

The sample size is n=55 and the population standard deviation is 6.

The significance level is 0.05.

We can calculate the standard error as:

$\sigma_M=\dfrac{\sigma}{\sqrt{n}}=\dfrac{6}{\sqrt{55}}=0.809$

For a significance level of 0.05, the critical value for z is zc=1.644. If the test statistic is bigger than 1.644, the null hypothesis is rejected.

a. If the sample mean is M=52.5, the test statistic is:

$z=\dfrac{M-\mu}{\sigma_M}=\dfrac{52.5-50}{0.809}=\dfrac{2.5}{0.809}=3.09$

The null hypothesis is rejected, as z>zc and falls in the rejection region.

b. If the sample mean is M=51, the test statistic is:

$z=\dfrac{M-\mu}{\sigma_M}=\dfrac{51-50}{0.809}=\dfrac{1}{0.809}=1.24$

The null hypothesis failed to be rejected, as z<zc and falls in the acceptance region.

c. If the sample mean is M=51.8, the test statistic is:

$z=\dfrac{M-\mu}{\sigma_M}=\dfrac{51.8-50}{0.809}=\dfrac{1.8}{0.809}=2.22$

The null hypothesis is rejected, as z>zc and falls in the rejection region.

8 0

4 years ago

Kassie is measuring two line segments. the first line segment is 35 centimetres long. the second line segment is 450 milimetres

Free_Kalibri [48]

1cm = 10mm
the 1st line segment is 35cm = 350mm
the 2nd line segment is 450mm = 45cm

6 0

3 years ago

In triangle XYZ, the length of side XY is 23 mm and the length of side YZ is 36 mm. Which of the following could be the length o

svlad2 [7]

Answer: The correct answer is Choice D, 43 mm.

When you know 2 sides of a triangle, you can find the range for the final side of the triangle.

First, if we subtract 36 - 23 = 13, the third leg must be more than 13. Otherwise, the two smaller legs would not meet to make the third leg.

Second, if we add 36 + 23 = 59, the third leg must be less than 59. Otherwise, the third leg would reach further than the other two legs could reach.

43 is the only number larger than 13 but smaller than 59 in our list.

7 0

3 years ago

**view image**

vladimir1956 [14]

The chart has been completed in the picture attached.

Step-by-step explanation:

Step 1:

It is given that the number of bacteria doubles every 6 hours.

So if there are 1 million now, in 6 hours there would be double that i.e. 2 million and it will go on.

Step 2:

As the first column says the number of 6-hour periods, the second column is the actual number of hours.

So the second column is multiples of 6 so the second column is filled with;