70, 62, 65, 83.
2007-04-23 14:49:49 · 6 answers · asked by prc85040 3 in Science & Mathematics ➔ Mathematics
70, 62, 65, 83. = mean of 70
10 less is 60
so (280 +x ) / 5 = 60
x = 20
2007-04-23 14:55:50 · answer #1 · answered by ignoramus 7 · 0⤊ 0⤋
You can solve this problem using simple algebra skills.
Our set of numbers is 70, 62, 65, 83, x. Where x is the number for which we must add to the group.
Now we must find the average of our set by adding up all of the numbers & dividing by 5 (the # of numbers in the set).
(70 + 62 + 65 + 83 + x) / 5 = (280 + x) / 5
The problems tell us that we want to now when the mean (average) is at least 10 less than the average of the given set (70, 62, 65, 83).
(70 + 62 + 65 + 83) / 4 = 280/4 = 70
There we are. Now we just need to set up an equation. According to our given information, the average of the final set (70, 62, 65, 83, x) is equal to 10 less the initial average (70 -10). Therefore...
(280 + x) / 5 = 70 - 10
(280 + x) / 5 = 60
280 + x = 300
x = 300 - 280
x = 20
The answer is 20!
Hope this was helpful!
2007-04-23 22:02:37 · answer #2 · answered by clueloopy_38 2 · 0⤊ 0⤋
I think you're saying you want to add a fifth number to the list to make the average 10 lower than it stands right now.
first calculate the average of the number given
=(70 + 62 + 65 + 83)/4
= 70
*So from this you can say that you want a fifth number that will make the average 60.
So no you can just plug in an x and solve the equation.
60 = (x +70 + 62 +65 +83)/5
300 = x +70 + 62 +65 +83
x = 20
-x must be 20 or less to make the mean reduce by at least 10.
2007-04-23 22:01:51 · answer #3 · answered by Odog 1 · 0⤊ 0⤋
To figure this problem out you should first find out what the average is right now (70)
To get the average down to 60 you should set up an equation such as (70+62+65+83+x)/5=60
Then multiply each side by 5 so the equation looks likt 70+62+65+83+x=300
or 280+x=300
then subtract 280 from three hundred to get you answer
2007-04-23 21:57:27 · answer #4 · answered by Liz 1 · 0⤊ 0⤋
The current mean is 70, so if 20 is added to the group, the new mean will be (4*70 + 20)/5 = 60.
2007-04-23 21:55:16 · answer #5 · answered by Phineas Bogg 6 · 0⤊ 0⤋
The average of those is 70. If we want to bring down the average by 10, then you need to have a value that compensates for every other value in that set. Let's take the difference between every number and 60
10,2,5,23
sum those to get 40. So our value needs to be 40 less than 60 so 20.
As expected the average of 20,70,62,65,83 is 60
2007-04-23 21:57:02 · answer #6 · answered by jerryjon02 2 · 0⤊ 0⤋