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2 years ago

7 x [(7 + 7) = 7 Help plz

Mathematics

1 answer:

tatuchka [14]2 years ago

6 0

Answer:

$\frac{1}{14}$

Step-by-step explanation:

7 x (7+7)=7

7x [(14)]=7

$x = \frac{1}{14}$

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Calculate the sample mean and sample variance for the following frequency distribution of heart rates for a sample of American a

spin [16.1K]

Answer:

$Mean = 68.9$

$s^2 =18.1$ --- Variance

Step-by-step explanation:

Given

$\begin{array}{cccccc}{Class} & {51-58} & {59-66} & {67-74} & {75-82} & {83-90} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

Solving (a): Calculate the mean.

The given data is a grouped data. So, first we calculate the class midpoint (x)

For 51 - 58.

$x = \frac{1}{2}(51+58) = \frac{1}{2}(109) = 54.5$

For 59 - 66

$x = \frac{1}{2}(59+66) = \frac{1}{2}(125) = 62.5$

For 67 - 74

$x = \frac{1}{2}(67+74) = \frac{1}{2}(141) = 70.5$

For 75 - 82

$x = \frac{1}{2}(75+82) = \frac{1}{2}(157) = 78.5$

For 83 - 90

$x = \frac{1}{2}(83+90) = \frac{1}{2}(173) = 86.5$

So, the table becomes:

$\begin{array}{cccccc}{x} & {54.5} & {62.5} & {70.5} & {78.5} & {86.5} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

The mean is then calculated as:

$Mean = \frac{\sum fx}{\sum f}$

$Mean = \frac{54.5*4+62.5*3+70.5*11+78.5*13+86.5*4}{6+3+11+13+4}$

$Mean = \frac{2547.5}{37}$

$Mean = 68.9$ -- approximated

Solving (b): The sample variance:

This is calculated as:

$s^2 =\frac{\sum (x - \overline x)^2}{\sum f - 1}$

So, we have:

$s^2 =\frac{(54.5-68.9)^2+(62.5-68.9)^2+(70.5-68.9)^2+(78.5-68.9)^2+(86.5-68.9)^2}{37 - 1}$

$s^2 =\frac{652.8}{36}$

$s^2 =18.1$ -- approximated

5 0

2 years ago

What is the sum of two odd numbers of 36

irakobra [83]

The sum of two odd numbers is 23+13. One way you could figure it out is to use your logic thinking! Hope this helps and I hope that you get this answer before the moderater deletes it! (They hate me! ☹️ I don't know what I ever done to them I just started today)

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3 years ago

2/5+x=1 What equals x?

kolbaska11 [484]

Answer:

Step-by-step explanation:

2/5 + x = 1

Multiply each term by 5

2 + 5x = 5

5x = 5 - 2

5x = 3

x = 3/5

8 0

3 years ago

Read 2 more answers

Help it’s for my babies brother hw

kodGreya [7K]

Answer:

From left to right, -3/2, -4/5, -3/10, 1/2, 7/8, 4/3

Step-by-step explanation

So what we're trying to do here is to order the numbers from greatest to least.

Let's start off with the negative numbers.

-3/10, -4/5, -3/2.

Now what we want to do is give them all a common denominator to figure out which one is the least of that group.

-3/10,-8/10,-15/10.

Now on to the positive numbers.

1/2, 4/3, 7/8

Turn the denominator into 24.

12/24, 32/24, 21/24

Then put them all in order.

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2 years ago

Read 2 more answers

A student earns an 80% on their science test. If she got 20 questions correct, how many total were on the test?

galina1969 [7]

25 questions
Explanation: 20 divided by 25 is .8 which is 80%

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2 years ago