Model 6  Efficiency of the worker Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (c)

Using Rule 2,

If Tapas alone takes x days to complete the work, then

$1/x + 1/{2x} = 1/12$

${2 + 1}/{2x} = 1/12$

$2x = 36 ⇒ x = 18$ days

Answer: (d)

Time taken by Sonia = 3x days (let)

Time taken by Pratibha = x days

3x - x = 60 ⇒ 2x = 60 ⇒ x = 30 days

Time taken by Sonia = 3x days

= 3 × 30 = 90 days.

Answer: (d)

Let B does the whole work in x days

Work done by B in 1 day = $1/x$

According to question

A does the $1/2$ work in $x/6$ days

A does the whole work in ${2x}/6 or = x/3$ days

Work done by A in one day = $3/x$

Work done by A and B together in one day

= $1/x + 3/x = 4/x$

Time taken to complete the whole work by A and B together

= $1/{4/x} = x/4$ days

Again, given that $x/4$ = 10 ∴ x = 40 days

Here, n = 3, d = 10

A is 3 times more efficient thanB.

Time taken by B = (n + 1) × D

= (3 + 1) × 10 = 40 days