## Chapter 10: CHAIN RULE

Q. If 15 toys cost Rs, 234, what do 35 toys cost?
A. 15: 234 :: 35 : x ; 15 * x = 234 * 35; thus we can find 'x'.

Q.
If 36 men can do a piece of work in 25 hours, in how many hours will 15 men
do it ?
A. 36 : 25 :: 15 : x we can use above formula to get 'x'.

Q. If the wages of 6 men for 15 days be Rs.2100, then find the wages of
for 12 days.
A. If 6 men worked for 15 days they spent 6*15 = 90 man days. They got 2100
for 90 man days and we need to calculate how much wage will 6 men working
for 12 days i.e. 72 man days should get.
So 90: 2100 :: 72 : x and solving this we get x = 2100 * 72 / 90.

Q. If 20 men can build a wall 56 metres long in 6 days, what length of a similar
can be built by 35 men in 3 days?
A. 20 men working for 6 days put in 120 man days and got 56 m so 35 * 3 man
days how much long wall we get is given by
120: 56 :: 35*3 : x
x = 35 * 3 * 56 / 120 = 49m

Q.  If 15 men, working 9 hours a day, can reap a field in 16 days, in how many
days will 18 men reap the field, working 8 hours a day?
A. 15 men * 9 hrs * 16 days put 15*9*16 work and we know that same work
can be done by 18*8*x [x = days].
15*9*16 = 18*8*x so x = 15 days

### Quiz

Score more than 80% marks and move ahead else stay back and read again!