i need a simple formula for this type of question.........?

Question

i need a simple formula for this type of question.........

3 boys can dig 5 wells in 2 days
how many wells can 2 boys dig in 3 days?
sometimes you can be asked to tell the number of boys or days.
i need a simple and general formula

Answer 1

THE FORMULA CANNOT BE GENERALISED
AS IT DEPENDS ON THE GIVEN DATA IF DAYS , WELLS, AND NO. OF BOYS IS GIVEN THEN THE GENERALISED FORMULA IS
LET NO OF BOYS BE X AND Y
AS THE NUMBER OF BOYS WHO WORK GO ON INCREASING THE NUMBER OF WELLS DIGGED ALSO GOES ON INCREASING
LET THE NO OF WELLS BE A AND B
X / Y = A / B
LET NO OF DAYS BE C AND D
AS THE NUMBER OF BOYS GOES ON INCREASING NO., OF DAYS GOES ON DECREASING AND SO
X / Y= A / B * D / C
THE ANSWER TO YOUR QUESTION IS 5 WELLS

Answer 2

If you think about it, "days" is the time to perform work and "boys" is the amount of work you can perform in a certain amount of time. Hence, if you multiply the number of days by the number of boys you get a total amount of work (call it a boy-day). It would then take so many boy-days to dig so many wells.

In the example you provided it would take 3 boys times 2 days, or 6 boy-days to dig 5 wells. Notice that 2 boys and 3 days is also 6 boy-days. Hence, you can expect to have the same number of wells (5) dug.

In general, using "d" for days, "b" for boys,. and "w" for wells, you'd need this formula below...

--- 3b * 2d = 5w
--- 6bd = 5w
--- bd = (5/6)w

As long as the rate of work is the same, just multiply the number of boys and days together and multiply by 5/6 to get the number of wells. If the assumed rate of work changes, just insert the new numbers in the first equation I have there and work that equation as normal.

Answer 3

all the answers given are correct. Don't try to solve this problem by remembering a formula since it's hard to solve it that way.

First of all, u need to calculate the no. of wells that can be made by 3 boys in 1 day i.e. 5 / 2 wells =2.5 wells
Now, 3 boys dig 2.5wells in 1 day, so how much portion of well can be done by 1 boy = (2.5) / 3

So for calculating the no. of wells that can be made by 2 boys in 1 day
= (2.5/3)*2 = 5/3

Finally, the total no. of wells that can be made by 2 boys in 3 days = (5/3)*3 =
5 wells

Answer 4

Just figure out what each boy can do in one day:

3 boys, 5 wells, 2 days
3 boys, 2.5 wells, 1 day
1 boy, 5/6 well, 1 day

Each boy can dig 5/6 of a well in a day.

So in 3 days, 2 boys can dig 5 wells.

Answer 5

First you need to calculate how much well one boy can dig in one day.
so do wells/boys/days = 5/3/2 = 5/6
then multiply up the boys and wells and wells per boy day in the second part of the question, giving
2 x 3 x 5/6 = 5 wells

Answer 6

If I still remembered my algebra correctly, the answer would be 5 wells.

That type of problem is a combination of direct variation and inverse variation. Direct variation is simply known as ratio and proportion and you can solve this by dividing. While indirect variation is the opposite of direct variation, meaning, that you solve this by multiplication.

For example, there are 5 machines that can make 10 bags. How many machines are needed to make 20 bags? The equation would be 5/10 = x/20. Just solve for x. This is a direct variation wherein one is increased and the other also increases.

For indirect variation, on the other hand, is when the two things are indirectly proportional. One decreases while the other increases. Like, there are 20 people and 10 kilograms of rice. How many people can eate 5 kilograms of rice? The equation is 20(10)=5x. Again, solve for x.

In your problem, we have (3x2)/5 = (2x3)/x.

Answer 7

5=2
1=x

Answer 8

boys wells days
3 5 2
2 x 3

first decide whether the no of wells dug will be more or less if the no of boys is less.obviously less.so choose the smaller of the two ratios 2/3.
if the no of days is more the no of wells dug will be more and so choose the bigger of the two possible ratios 3/2
now x=2/3*3/2*5=5 wells
this is the compounded ratio method
good luck

Answer 9

in 1 day 3 boys can dig 2.5 holes(divide 5 by 2)
in 1 day 1 boy can dig .83 holes(divide 2.5 by 3)
in 1 day 2 boys can dig 1.667 holes(multiply .83 times 2)
n 3 days 2 boys can dig 5 holes(multiply 1.667 tmes 3)

Your answer s 5 holes.

Answer 10

The formula is:

W1/(B1*D1) = W2/(B2*D2)

where,
W is number of wells
B is number of boys
D is number of days
and the subscripts 1 and 2 stand for cases 1 and 2

As already solved by others, for your example :
B1=3,B2=2, D1=2, D2=3 and W1=5 gives W2=5 wells