maths - find the mean plz help!!?

Question

shoe sizes = 5 , 6 , 8 , 7.5 , 5 , 3 , 6 , 6 , 4 , 7
the mean is 5.75!
susan adds her own shoe size which makes the mean 6
what is susans show size?

can someone help me to work this out please! i dont want the answer just help on how to do it please!!!

Answer 1

The mean is the sum of the numbers divided by the count.

So, when you add up the numbers above, you get 57.5. There are 10 shoe sizes, so you divide by 10 to get 5.75. That is your mean.

When you add Susan's shoe, the mean becomes 6. The count goes from 10 to 11. With 11 items, you get a mean of 6 only if they add up to 66. You currently have 57.5, so you need to figure out what shoe size brings the total to 66.

66 – 57.5 = 8.5

So, Susan's shoe size mus be 8.5 to bring the total up to 66 and thus the mean of 6.

Answer 2

To start with, there are ten shoe sizes. these are the sizes of 10 different people.

You get the (arithmetical) mean by adding up all the numbers and dividing by how many there are (in this case 10)

At first the mean = 57.5/10

=5.75

When Susan joins the group there are now 11 people.

These 11 people have a mean shoe size of 6.

You need to find the number which when divided by 11 gives 6

This is 66

The sum of all 11 shoe sizes, including Susan's is 66

The sum of the shoe sizes without Susan's was 57.5

So Susan's shoe size is the difference between these two values.

Susan's shoe size is 66 - 57.5

=8.5

Susan's shoe size is 8.5 (This is the way to do the sum.)

Answer 3

Susan's shoe size is 8.5 You add up all the shoe sizes to get 57.5 for the total of 10 pairs of shoes. You divide the number by the number of shoes sizes which is10 sizes and you get a mean of 5.75. If you add Susan's shoe size you now have 11 shoe sizes. You know the mean is 6 so you have to multiply by 11 to get the total for all 11 sizes which is 66. You then take away 57.5 from 66 and you get left with Susan's shoe size which is 8.5.

Answer 4

Susan has pretty big shoes!
With Susan's, there will be a total of 11 shoe sizes with a mean of 6. So the total of all shoe sizes will be 11*6=66
The total of the 10 first shoe sizes is 57.5
So Susan's shoe size is 66-57.5 = 8.5

Answer 5

This one is simple, once you know the formula being used.

Any time an average (or "mean") is calculated, all the data are first added together, and then divided by the number of entries.

The given data (without Susan) contain 10 entries. This means:

[everything added together] / 10 = 5.75

Multiply both sides by 10 if you're interested in finding the total of all the shoe sizes:

[everything added together] = 57.5

But adding Susan brings the total number of entries to 11, and adds an unknown shoe size (we'll call it X) to the mix. Thankfully, we are given the right side of the equation, the mean:

[57.5 + X] / 11 = 6

As before, let's multiply by 11:

[57.5 + X] = 66

Now, just subtract the 57.5 from both sides:

X = 8.5

And that's Susan's shoe size!

Answer 6

The mean of the shoes is 5.75
so if susan adds hers they become 6
therfore (6-5.75=0.25)

checking if ans is correct
Thus the differance between the 2 means is 0.25
Then reverse all the process i.e to include the 2.5{becomes 2.5 since it is multiplied by 10 to become right since the diff 0.25 is the mean difference)

57.5 is the addition of the shoe sizes before thus we add theother pair)
2.5+57.5= 60
60/11=6

Thus mean ans is correct susans shoe size is 2.5

Answer 7

You find the mean by dividing the total sum of the scores by the amount of scores that are there.
So, do the opposite.
For example, with the 5.75 you have 10 scores. So, mutiply by the 5.75 by 10; you get 57.5, the sum of the scores (57.5 divided by 10 is 5.75).
So, with to figure out what makes the mean 6 you have to first figure out your amount of scores you now have with one additional score added, then mutiply the amount by 6. Then, subtract that amount from the original sum to get your answer.

Or, in algebraic form, wherein x is the shoe size your looking for:
57.5 + x = 66
Did that make any sense?

Answer 8

turn it into an equation then solve for x.

(5+6+8+7.5+5+3+6+6+4+7+x)/11=6

Answer 9

There are ten sizes in the set, each one 0.25 less than the required new mean.
Susan's size must be 6 + 10*(6-5.75) = 8.5
Pretty big for a girl.

Answer 10

mean of 10 sizes = 5.75
Therefore sum of sizes = 5.75 * 10
= 57.5

New mean after 11th size added = 6
Therefore sum of 11 sizes = 66
Thus 11th size = 66 - 57.5
= 8.5

So Susan's shoe size is 8.5