100+ Chain rule problems for Bank exams - 1

Ans: B

Let the required number of men be x.

Less days, More men (Indirect Proportion)

More working hrs per day,

Less men (Indirect Proportion)

∴ 8 × 15 × x = 10 × 8 × 12

⇔ x = ${10 × 8 × 12}/{8 × 15}$ ⇔ x = 8.

Ans: C

Cost of x metres = Rs.d.

Cost of 1 metre = Rs.($d/x$).

Cost of y metres = Rs.($d/x$ × y) = Rs.(${yd}/x$).

Ans: C

Let the required number of labourers be x. Then,

Less working hrs/day, More labourers (Indirect Proportion)

More days, Less labourers (Indirect Proportion)

∴ 6 × 30 × x = 7 × 18 × 30 ⇔ 6x = 126 ⇔ x = 21.

Ans: C

Let the total number of men be x.

Work done = $1/3$, Remaining work = $(1 – 1/3) = 2/3$

More work, More men (Direct Proportion)

More days, Less men (Indirect Proportion)

∴ $(1/3 × 25 × x) = (2/3 × 20 × 20) ⇔ x = 800/25 = 32.$

∴ More men to be employed = (32 – 20) = 12.

Ans: B

Let the required number of working hours per day be x.

More pumps,

Less working hours per day (Indirect Proportion)

Less days,

More working hours per day (Indirect Proportion)

∴ 4 × 1 × x = 3 × 2 × 8

⇔ x = ${3 × 2 × 8}/4$ ⇔ x = 12.