I have the answer to this, too - but I may be doing it wrong.
If 6 men can do a piece of work in 14 days, how many men are needed to do the work in 21 days?
The easy answer is 9 (it takes 1 man to do a job in 7 days, making 9 men in 21 days.) But the answer here as "correct" is 4 men in 21 days - which could also make sense, but I don't know how to get to that answer?
Does anyone have the solution - something that actually makes logical mathematical sense - and with the working out please. Thank you! :)
2006-07-02 07:16:47 · 10 answers · asked by Iram 3 in Science & Mathematics ➔ Mathematics
Okay - all of those are good - but I need to know why you would do 14 x 6 - is this another formula? I did 6/14 = x/21 and then cross multiplied, but x=9. So what was I doing wrong?
2006-07-02 07:33:35 · update #1
mathsmart - I liked your explanation the best, but nicegal also did it very nicely and she did it before you. :) Great job to both you math whizzes - I need to polish up on my skills!
2006-07-02 08:06:25 · update #2
total work = 14*6 man-days
men to do it in 21 days = 14*6/21 = 4
2006-07-02 07:20:58 · answer #1 · answered by Anonymous · 0⤊ 0⤋
If 6 men do the job in 14 days, that means that 6 men do 1/14th of the job in 1 day. Divide that by 6 to find that 1 man does 1/84th of the job in 1 day.
Now, we have 21 days, so if 1 man does 1/84th of the job in 1 day, in 21 days 1 man will do 21 times that or 21/84ths of the job. This reduces to 1/4, so one man can do one fourth of the job in 21 days. That means 4 men can do the whole job in 21 days.
2006-07-02 08:00:03 · answer #2 · answered by mathsmart 4 · 0⤊ 0⤋
The answer is as follows
6 men do a work in 14 days.
So 6 men complete a work...
So contribution by each towards work =1/6
And work is completed in 14 days
So each days work = 1/14
Now the same work wil b done in 21 days.
Let men requied be y
So each man's contribution wil b 1/y
So 1/y = (1/14 )x 21 x (1/6)
1/y = 1/4
So y = 4.
2006-07-02 07:32:09 · answer #3 · answered by nicegal 3 · 0⤊ 0⤋
the answer goes like this
ment at work 6
number of days 14
equation is 14: 21= 6: x
or 14 x 6 =X x 21
or x = 84 / 21
answer is 4
so 4 men are required to work to complete in 21 days
2006-07-02 07:26:59 · answer #4 · answered by abhinav m 1 · 0⤊ 0⤋
algebraically speaking, 9 is correct when the math is performed as a proportion and cross multiplied. Now, if we're speaking ability to perform the task: If it is physical strength that is required that's a different situation compared to mental strength. I too would like to know how 4 men in 21 days would be the answer.
2006-07-02 07:30:29 · answer #5 · answered by sweetpea 1 · 0⤊ 0⤋
One man works 7 days,
another works 7 days,
another works 7 days too,
andthen 1 more man works 7 days.
Four men times 7 days of work will equeal to what you said was the right answer is, 4 men work in 21 days.
2006-07-02 07:32:49 · answer #6 · answered by jake_black94 2 · 0⤊ 0⤋
6 men times 14 days = 84 men days. 84 men days divided by 21 days = 4 men
2006-07-02 07:24:48 · answer #7 · answered by Joseph Binette 3 · 0⤊ 0⤋
14 is 2/3rds of 21
2006-07-02 07:23:25 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Make a shortcut
REmember there is something in these tpe questions that is always constant.
Here the work is constant so that employes
6*14=A*21
where A is the number of men
So the answer is 4.
Just remember there is something which is constant (always).
2006-07-02 08:45:50 · answer #9 · answered by The Game BOY ! 1 · 0⤊ 0⤋
good question!
2006-07-02 07:27:26 · answer #10 · answered by Anonymous · 0⤊ 0⤋