Question
4 men and 2 boys together can complete a work in 18
days. 2 men and 6 boys can together complete half of the same work in 9 days. Find the time taken by 1 man and 1 boy together to complete 75% of the entire work.Solution
Let the efficiency of man and that of a boy be 'M' units/day and 'B' units/day respectively. Time taken by 2 men and 6 boys together to complete the entire work = 9 × 2 = 18 days Then, total work = (4M + 2B) × 18 = (2M + 6B) × 18 Or, 4M + 2B = 2M + 6B Or, 2M = 4B So, M : B = 2 : 1 Let 'M' = 2x and 'B' = x Then, total work = (2x × 4 + x × 2) × 18 = (8x + 2x) × 18 = 10x × 18 = 180x units 75% of the total work = 180x × 0.75 = 135x units Time taken by 1 man and 1 boy together to complete 75% of the work = 135x ÷ (2x + x) = 135 ÷ 3 = 45 days
- A class of 20 students has an average age of 19 years. 5 new students join and the average becomes 17.5 years. Find the average age of the new students.
- The average of ‘x’ numbers is 18. If 40% of the numbers are decreased by 4 and the remaining numbers are increased by 6, then find the new average of t...
The average temperature for a week is recorded as 35.4°C. The difference between the highest and lowest temperatures during the week is 30°C. Addition...
2 years ago, the average age of the family of 3 members is 13 years. A baby is born now; the average age of the family is same as before. Find the age o...
- The average marks of Karan in 5 different papers was calculated as 73. But it was later found that his marks in two subjects were wrongly entered as 80 and...
Average marks scored by each boy in a class were 95, whereas that by each girl were 105. If the number of boys is 50% more than the number of girls, the...
- There are three numbers 'p', 'q' and 'r' such that average of 'p' and 'q' is 12, average of 'q' and 'r' is 28 and average of 'p' and 'r' is 20. Find the av...
The average age of Anuj, Saroj and Tanuj is 36 years. The average age of Anuj and Saroj is 30 years, while the average age of Tanuj and Anuj is 36 years...
If average of first 10 numbers is (n – 23) and the sum of remaining number is 925. Find the value of ‘n’, if the average of 20 numbers is ‘n’....
Average of 8 numbers is 25. If average of first four and last two numbers is 15 and 40, respectively then find the fifth number given that ratio of fift...
Relevant for Exams:
