The average weight for a group of 20 women is 130 pounds. If the average weight for 3/4 of these women was 140 pounds, what was the average weight, in pounds, for the rest of the women?
I figured out the answer by just thinking about it but would like to know how to set up a formula/problem to solve for x. I'm a little rusty with my algebra. Thanks.
2007-06-07 15:52:59 · 3 answers · asked by justmeeh 2 in Science & Mathematics ➔ Mathematics
The average weight of 20 women is 130 pounds.
Hence, the total weight of the women is 20*130 = 2600 pounds.
The average weight of 3/4 of the women is 140 pounds.
The total weight of these women is 15*140 = 2100 pounds.
The remaining 5 women weigh 2600 - 2100 = 500 pounds.
Hence, the average weight of the remaining women is 100 pounds.
In formula terms:
Let x be the avg weight of the remaining women.
(1/4)*20*x + (3/4)*20*140 = 20*130
5x + 15*140 = 20*130
5x = 20*130 - 15*140
5x = 2600 - 2100
5x = 500
x = 100
Hope that helps!
2007-06-07 16:02:18 · answer #1 · answered by Bramblyspam 7 · 1⤊ 0⤋
Weight for 20 women is 130 avg
Weight for 15 women is 140 avg
20 women weigh 20*130 or 2600 pounds
15 women weigh 15*140 or 2100 pounds
Subtract
5 women weigh 500 pounds or an average of 100 pounds
2007-06-07 23:02:26 · answer #2 · answered by gordonmorrison 6 · 0⤊ 0⤋
3/4*140 + 1/4 * X = 4/4 * 130
X= 4*130-3*140 = 100
2007-06-07 23:00:50 · answer #3 · answered by telsaar 4 · 0⤊ 0⤋