Question

pls ans question of work and time pls ans correctly​

Answer 1

Step-by-step explanation:

10)

A's one day work = 1/10

B's one day work = 1/12

C's one day work = 1/15

(A + B + C)'s one day work:

$\dfrac{1}{10}+\dfrac{1}{12}+\dfrac{1}{15}$

$=\dfrac{6+5+4}{60}$

$=\dfrac{15}{60}$

$=\dfrac{1}{4}$

Work left after A leaves:

$1-\dfrac{1}{4}$

$=\dfrac{4-1}{4}$

$=\dfrac{3}{4}$

(B + C)'s one day work:

$\dfrac{1}{12}+\dfrac{1}{15}$

$=\dfrac{5+4}{60}$

$=\dfrac{9}{60}$

$=\dfrac{3}{20}$

Work left after B leaves:

$\dfrac{3}{4}-\dfrac{3}{20}$

$=\dfrac{15-3}{20}$

$=\dfrac{12}{20}$

$=\dfrac{3}{5}$

As, C does 1/15 work in one day.

Therefore,

$\sf{C\: can \: complete\:\dfrac{3}{5}\: work\: in:}$

$\dfrac{3}{5}\div\dfrac{1}{15}$

$\dfrac{3}{5}\times15$

$\dfrac{3}{1}\times3$

$\dfrac{9}{1}$

$9$

Hence, C can complete the remaining work in $\sf{9}$ days.

-------------------------

11)

A's one day work = 1/10

B's one day work = 1/15

(A + B)'s two day work if they work alternatively:

$\dfrac{1}{10}+\dfrac{1}{15}$

$=\dfrac{3+2}{30}$

$=\dfrac{5}{30}$

$=\dfrac{1}{6}$

Time taken to complete the work:

$1\div\dfrac{1}{6}$

$=1\times6$

$=6$

Because we calculated (A + B)'s two day work.

Therefore we will multiply the result by 2.

Multiplying the result by 2:

6 × 2

= 12

Hence, the work will be completed in 12 days.

-------------------------

12)

Let us assume:

• B can complete the work in 2x days.

Then,

• A can complete the work in x days.

Hence,

• A's one day work = 1/x
• B's one day work = 1/2x

Because,

(A + B) can complete the work in 14 days.

Therefore,

(A + B)'s one day work = 1/14

Transposing the values,

$\dfrac{1}{x}+\dfrac{1}{2x}=\dfrac{1}{14}$

$\dfrac{2+1}{2x}=\dfrac{1}{14}$

$\dfrac{3}{2x}=\dfrac{1}{14}$

By cross multiplication:

2x = 3 × 14

2x = 42

x = 21/2

x = 21

Hence, x = 21

Therefore, A can complete the work in 21 days.

-------------------------

13)

Let us assume:

• B can complete the work in 3x days.

Then,

• A can complete the work in x days.

Hence,

• A's one day work = 1/x
• B's one day work = 1/3x

Because,

(A + B) can complete the work in 15 days.

Therefore,

(A + B)'s one day work = 1/15

Transposing the values,

$\dfrac{1}{x}+\dfrac{1}{3x}=\dfrac{1}{15}$

$\dfrac{3+1}{3x}=\dfrac{1}{15}$

$\dfrac{4}{3x}=\dfrac{1}{15}$

By cross multiplication:

3x = 4 × 15

3x = 60

x = 60/3

x = 20

Hence, x = 20

Therefore, A can complete the work in 20 days.

-------------------------

14)

12 men can do a work in 8 days.

1 man can do the work in (8 × 12) days.

= 96 days [less men, more days]

16 men can do the work in (96/16) days.

= 6 days [more men, less days]