# CHAIN RULE

1. Explanation :

Let the required cost be Rs. x.
Then, More toys, More cost (Direct Proportion)

15 : 35 : : 234 : x
(15 * x) = (35 * 234)
x=(35 * 234)/15 = 546
Hence, the cost of 35 toys is Rs. 546.

1. Explanation :

. Let the required number of hours be x.
Then, Less men, More hours (Indirect Proportion)

15 : 36 : : 25 : x
(15 x x) = (36 x 25)
(36 x 25)/15 = 60
Hence, 15 men can do it in 60 hours.

1. Explanation :

Let the required wages be Rs. x.
More men, More wages (Direct Proportion)
Less days, Less wages (Direct Proportion)
Men 6: 9 : :2100:x
Days 15:12
Therefore (6 * 15 * x)=(9 * 12 * 2100)
x=$$\frac{(9 * 12 * 2100)}{(6 *15)}$$=2520
Hence the required wages are Rs. 2520.

1. Explanation :

Let the required length be x metres
More men, More length built (Direct Proportion)
Less days, Less length built (Direct Proportion)
Men 20: 35
Days 6: 3 : : 56 : x
Therefore (20 x 6 x x)=(35 x 3 x 56)
x=(35 x 3 x 56)/120=49
Hence, the required length is 49 m.

1. Explanation :

1. Explanation :

. Let 3 engines of former type consume 1 unit in 1 hour.
Then, 4 engines of latter type consume 1 unit in 1 hour.

1. Explanation :

1. Explanation :

The problem becomes:
3300 men taking 850 gms per head have provisions for (32 - 7) or 25 days, How many men taking 825 gms each have provisions for 17 days?
Ration 825 : 850
Days 17: 25 } : : 3300 : x
(825 x 17 x x) = 850 x 25 x 3300 or x = (850 x 25 x 3300)/(825 x 17)=5000
Strength of reinforcement = (5500 - 3300) = 1700.