A research team estimates that 30% of their questionnaires will not be returned. How many questionnaires should they mail out in order to be reasonably certain that at least 750 will be returned? thanks!
2006-09-17 15:32:28 · 11 answers · asked by jason 1 in Science & Mathematics ➔ Mathematics
Think of it this way: Their estimate is that 30% of the questionnaires will not be returned, so therefore 70% will be returned, right? So what we're saying is that 70% of the total number of questionnaires mailed out will equal 750. In an equation, with total number of questionnaires represented by X, you get
0.7 X = 750
Rearrange and solve, and X = 750/0.7 = 1071.42
Since you can't send out 0.42 questionnaires, you round up and send out 1072.
(In reality, of course, you realize that 30% is only an estimate, and you should send out 1500 just in case; you'll still get AT LEAST 750 back even if your estimate was off by up to 20%.)
2006-09-17 15:37:52 · answer #1 · answered by theyuks 4 · 0⤊ 0⤋
The best way to answer this is to think that if 30% are not retunred, then 70% will be returned. If that 70% is 750 responses, you need to find out what 100% would be.
Let x = number that need to be mailed out.
0.70x = 750
Divide both sides by 0.7
x = 750/0.7
x=1071.4
So you need to mail out 1072 questionnaires.
2006-09-17 22:38:48 · answer #2 · answered by john977 2 · 0⤊ 0⤋
Let X = the total number they need to send out.
X - 3X/10 = 750
10X - 3X =7500
7X = 7500
X=1071.4285
Send out 1072 questionnaires
Proof: 30% of the 1072 won't be returned:
That's 322 questionaires.
1072 - 322 = 750 (returned)
2006-09-17 22:51:19 · answer #3 · answered by LeAnne 7 · 0⤊ 0⤋
.7(total number of questionnaires sent out) = 750
70% will be returned.
So now divide by .7 to solve the equation.
Hope this helps. Good Luck.
2006-09-17 22:34:49 · answer #4 · answered by SmileyGirl 4 · 0⤊ 0⤋
set 750 equal to the 70% that ARE returned.
2006-09-17 22:52:17 · answer #5 · answered by cdf-rom 7 · 0⤊ 0⤋
1072 questionnaires
2006-09-17 22:36:58 · answer #6 · answered by sandyclaws08 2 · 1⤊ 0⤋
Your problem boils down to: .7X=750. Solve for X.
Since X will be a decimal, round up.
2006-09-17 22:34:44 · answer #7 · answered by zex20913 5 · 0⤊ 0⤋
do 750 divided by 30%
2006-09-17 22:33:44 · answer #8 · answered by chiken nugget 2 · 0⤊ 1⤋
1072 fliers should be sent out at minimum
2006-09-17 22:35:11 · answer #9 · answered by bchylik 3 · 0⤊ 0⤋
2475
2006-09-17 22:35:46 · answer #10 · answered by blatt 4 · 0⤊ 1⤋