SOLUTION: (1). 8 labourers do a work in 50 days . if the number of men are doubled , then in how many days will the same work be done ? (2). 130 men dig a ttunnel in 170 days . how many me

Algebra ->  Average -> SOLUTION: (1). 8 labourers do a work in 50 days . if the number of men are doubled , then in how many days will the same work be done ? (2). 130 men dig a ttunnel in 170 days . how many me      Log On


   

Question 764402: (1).
8 labourers do a work in 50 days . if the number of men are doubled , then in how many days will the same work be done ?
(2). 130 men dig a ttunnel in 170 days . how many men will complete this task in 140 days ?
(3).
average of 5 numbers is 60 .sum of first two is 100 and last two is 160. find the fifth number??
Answer by josgarithmetic(39633) About Me  (Show Source):
You can put this solution on YOUR website!
Find the rates of one man, for your questions #1 and #2. The question parts will then be simple to answer.

You have the describable form, N laborers do a job in D days. The rate for one man is then N%2FN laborers does a job in D%2AN days. Think how that works! The rate for one man in DAYS per JOB would then be 1%2F%28D%2AN%29.

Next you want to understand that when workers are working at the same time, then their individual rates are added.

In both #1 and #2, you will use R%2At=j where R is the working rate, t is time, and j is how much or many jobs. In #1, the unknown variable to solve will be t. In #2, the unknown variable to solve will be part of the rate ----- a whole number factor representing the rate for the group of unknown quantity of workers.