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3 years ago

Sally is 54 years old and her mother is 80, how many years ago was Sally’s mother times her age?

Mathematics

2 answers:

atroni [7]3 years ago

6 0

Answer:

41 years ago, when Sally was 13

and her mother was 39.

I hope it will help you

I've seen this question somewhere

yanalaym [24]3 years ago

3 0

Answer:

<u>41 years ago</u>

Step-by-step explanation:

Let the no. of years ago be x.

Then, the equation we need would be :

=> 80 - x = 3(54 - x)

=> 80 - x = 162 - 3x

=> 2x = 82

=> x = 41

Sally's mother was 3 times her age <u>41 years ago</u>

Checking

=> Sally = 54 - 41 = 13

=> Mom = 80 - 41 = 39

=> 13 x 3 = 39 [∴Verified]

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3 years ago

Read 2 more answers

The table lists the speeds of the fastest roller coasters in North America and Asia.

kotykmax [81]

The difference of the means of the two data sets is = 4.57

The mean absolute deviation of the roller coaster speeds in North America is 13.3

The mean absolute deviation of the roller coaster speeds in Asia is 16.8

<h3>How to solve for the means</h3>

First we have to start with the data for North America

128, 120, 100, 93, 92, 80.8, 85, 82, 80, 77

To get the mean you have to sum up the values and divide through by the total number 10

937.8/10

Mean = 93.78

Mean Absolute Deviation = (128 - 93.78) + ( 120 - 93.78) + ( 100 - 93.78) + ( 93 - 93.78) + ( 92 - 93.78) + ( 80.8 - 93.78) + ( 85 - 93.78) + ( 82 - 93.78) + ( 80 - 93.78) + ( 77 - 93.78) / 10

133.32/10 = 13.3

For Asia, we have the data as

149.1, 106.9, 95, 83, 90, 80.3, 78.3, 71.5, 69.6, 68.4

Mean for Asia = 892.1/10

= 89.21

Mean Absolute Deviation = (149.1 - 89.21) + ( 106.9 - 89.21) + ( 95 - 89.21) + ( 83 - 89.21) + ( 90 - 89.21) + ( 80.3 - 89.21) + ( 78.3 - 89.21) + ( 71.5 - 89.21) + ( 69.6 - 89.21) + ( 68.4 - 89.21) / 10

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The difference in the means = 93.78 -89.21

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