Its me again and i have found myself stuck on another problem. however, i have reason to believe there is no answer to this problem but i want to check first. the problem goes like this:
Sadie is in Algebra II. she has made 82,98,76 and an 80 on four tests. what must she make on the fifth to have an average of 90.
i believe there is no answer because the total of the 4 tests come out to 336. naturally my first guess is that she makes a 100 and with that added to 336 that comes out to 436. however 436 divided by 500 is only an 87. so i believe there is no answer to this. however if there is an answer to this please show all work and how you got your answer
2007-08-22 14:30:28 · 8 answers · asked by Lil D 2 in Science & Mathematics ➔ Mathematics
90*5 = 450 - (82+98+76+80) = 114.
Sadie must make a 114 to have an average of 90 for the five tests.
You're correct. If 100 is the max, then 87 is the max you can make.
2007-08-22 14:35:38 · answer #1 · answered by Ferfull 2 · 0⤊ 0⤋
It depends on whether you are looking for a mathematical answer or whether your answer is constrained by real world considerations.
She actually needs to make a 114 to get a 90 average, and on a test, that is what I would put with the caveat, that in the real world such a score might not be attainable.
Did you know that you can do quick estimates of probs like these as follows:
the 82 is 8 below 90 and the 98 is 8 above 90 so those two cancel each other. The 76 is 14 below ninety and the 80 is ten below ninety so she must get 24 above ninety to have a ninety average.
it's a good way to get an estimate to show whether your ultimate answer is correct.
2007-08-22 21:38:13 · answer #2 · answered by VampireDog 6 · 0⤊ 0⤋
Using algebra, you would have to score above 100 to average a total of 90. So yeah, what you've said is partially correct.
(82 + 98 + 76 + 80 + x)/5 = 90
solve for x
(336 + x)/5 = 90
336 + x = 450
x = 114
you would have to score 114 to average 90.
*check by substitution*
(82 + 98 + 76 + 80 + 114)/5 = 90
2007-08-22 21:40:08 · answer #3 · answered by Anonymous · 1⤊ 0⤋
Well the answer would be 114 technically.
90=(x+336)/5
multiply both sides by 5 to get
450=x+336
subtract 336 from both sides and you get 114
hope that helped!
2007-08-22 21:41:17 · answer #4 · answered by hay 2 · 0⤊ 0⤋
Do not stop at 100 for the fifth. Try a number higher. You may not realistically be able to make more than 100 on a test without extra credit but that is the only way to get the correct answer.
2007-08-22 21:34:23 · answer #5 · answered by melya 4 · 0⤊ 0⤋
114%...
Umm How I solved it..
I don't know. Lol But its correct because if you add
114 + 82 + 98 + 76 + 80 you get 450. Divide by 5 to get the average and you get 90!
2007-08-22 21:37:10 · answer #6 · answered by Nick 3 · 0⤊ 0⤋
Yeah, you're right. She'd need a 114.
2007-08-22 21:36:49 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Looks OK to me. Don't be afraid to stand up and say there is no solution. Not every hw problem has one.
2007-08-22 21:36:07 · answer #8 · answered by cattbarf 7 · 0⤊ 0⤋