Question

Plz help with the task my child is trying to do

Answer 1

7

Explanation:

First, add all the cards.

`2 + 5 + 7 + 8 + 9 = 31`

If we remove one card, the remaining four cards average will be 6, this means that the 4 remaning cards will average total will be at 24 because 6×4=24. So we need to find a value that will equal 24 if we remove that card.

The answer is 7 because

`(2 + 5 + 8 + 9)/(4) = 6`

Answer 2

9514 1404 393

Answer:

remove 7 to make the total be 6×4 = 24.

Explanation:

The description "mean average" is redundant to no apparent purpose. "Mean" and "average" are the same thing: the total divided by the number of contributors.

If the mean of 4 cards is 6, then we require ...

6 = (total of 4 cards) ÷ 4

24 = total of 4 cards . . . . . . . multiply both sides of the equation by 4

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We note that the total of all the cards shown is ...

2 + 5 + 7 + 8 + 9 = 31

In order to make the total be 24, we need to remove a card that has a value of ...

31 -24 = 7

Removing 7 will bring the total to 2 + 5 + 8 + 9 = 24, and the average to 24/4 = 6.

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Additional comment

It is worthwhile to remember the relationship between the total and the average and the number of contributors. This shows up a lot in problems involving adjusting an average or finding a value to give a certain average.