18 girls can do piece of work in 12 days. 12 boys can do the same piec...
GIVEN:
18 g ⇒ 12 days
12 b ⇒ 9 days
FORMULA USED:
Total work = Total number of persons × Number of days
CALCULATION:
18 g × 12 = 12 b × 9
2g = 1b
Now, according to the question
Let the total work done by 8 boys and 8 girls be x days
then
(8b + 8g) × x = 18g × 12
(16g + 8g) × x = 18g × 12 or x = 18 × 12/24 = 9 days
View all questions of this test
18 girls can do piece of work in 12 days. 12 boys can do the same piec...
Given information:
- 18 girls can do a piece of work in 12 days.
- 12 boys can do the same piece of work in 9 days.
To find:
- In how many days will 8 boys and 8 girls complete that work?
Approach:
Let's assume that the total work to be done is 1 unit.
- So, 18 girls can do 1 unit of work in 12 days which implies that 1 girl can do 1/216th of the work in a day (because 1/12th of the work will be done by 18 girls in a day).
- Similarly, 12 boys can do 1 unit of work in 9 days which implies that 1 boy can do 1/108th of the work in a day (because 1/9th of the work will be done by 12 boys in a day).
Now, let's find out the work done by 8 girls and 8 boys in a day.
- Work done by 8 girls in a day = 8 × 1/216 = 1/27.
- Work done by 8 boys in a day = 8 × 1/108 = 1/13.5.
So, the total work done by 8 girls and 8 boys in a day = 1/27 + 1/13.5 = 5/54.
Therefore, the number of days required to complete the work by 8 girls and 8 boys = 1/(5/54) = 10.8 days ≈ 11 days.
Answer: The correct option is (D) 9 days.
Explanation:
- Let's consider the work to be done as 1 unit.
- Work done by 18 girls in a day = 1/12.
- Work done by 1 girl in a day = 1/12 × 1/18 = 1/216.
- Work done by 12 boys in a day = 1/9.
- Work done by 1 boy in a day = 1/9 × 1/12 = 1/108.
- Work done by 8 girls and 8 boys in a day = 8 × 1/216 + 8 × 1/108 = 5/54.
- Number of days required to complete 1 unit of work by 8 girls and 8 boys = 1/(5/54) = 10.8 days ≈ 11 days.
- So, the correct answer is (D) 9 days.