Twelve man take 6 hours to finish a piece of work. After the 12 men have worked for 1 hour, the contractor decides to call in 8 men so that the work can be completed earlier. How many more hours would 20 men take to complete the remaining work?
job requires 12(6) = 72 man-hours
They work for 1 hour, so 12 man-hours are used up, leaving 60 man-hours for the job to be done
Second shift has 20 men,
so time needed to complete the job
= 60 man-hours/20 men
= 3 hours
(the above applies only in theory, it does not apply to city workers or the like. Doubling the number of men on a job in practise does not cut the required time in half. , (this is supposed to be a joke) )
solution:
x=?
4x+2y=5------------1 Equation
3x+y=2-------------2 Equation
2 equation multiply by 2
6x+2y=4------------3 Equation
1 equation sub by 3 equation
6x+2y=4
+(-)4x+(-)2y=(-)5
--------------------------
2x=-1
x=-1/2
Thanks!
find the value of X
if 4x+2y=5 and 3x+y=2
To find the number of hours it would take for 20 men to complete the remaining work, we need to first determine the amount of work that was already done by the initial 12 men.
Given that 12 men took 6 hours to finish the work, we can say that the work done in 1 hour by these 12 men is 1/6th of the total work. Therefore, in the first hour, the initial 12 men completed 1/6th of the work.
Now, let's find out the amount of work that is still left to be done. Since the initial 12 men completed 1/6th of the work, the remaining work is 1 - 1/6 = 5/6.
Next, let's determine the rate at which the work can be done by 1 man. If 12 men can complete the work in 6 hours, then 1 man would take 12 times longer, which is 12 * 6 = 72 hours to complete the entire work.
Now, when the contractor calls in 8 more men, the total number of men working becomes 12 + 8 = 20 men.
Since we know that the work remaining is 5/6 and that the rate at which 1 man can complete the work is 72 hours, we can use this information to find the number of hours it would take for 20 men to complete the remaining work.
If 1 man takes 72 hours to complete the work, then 20 men will take 72 divided by 20, which is 3.6 hours.
Hence, it would take 20 men approximately 3.6 more hours to complete the remaining work.