Bilal can finish a work in 10 days. Jalal is twice as efficient as Bilal. If they work together, how many days will the work be finished?
A. 3 days
B. 6 days
C. 7 days
D. None of these
Explanation:
Let’s find out how much work Bilal and Jalal can do in one day individually.
Bilal can finish the work in 10 days, so his work rate per day is 1/10 (representing the fraction of work he completes each day).
Jalal is twice as efficient as Bilal, so his work rate per day is 2 * (1/10) = 1/5 (twice Bilal’s work rate).
Now, let’s calculate their combined work rate when they work together:
Combined work rate = Bilal’s work rate + Jalal’s work rate
Combined work rate = 1/10 + 1/5
Combined work rate = 1/10 + 2/10
Combined work rate = 3/10
To find out how many days it would take them to finish the work together, we divide 1 (the total work) by their combined work rate:
Time taken together = 1 / Combined work rate
Time taken together = 1 / (3/10)
Time taken together = 1 * (10/3)
Time taken together = 10/3
Now, we convert this improper fraction to a mixed fraction:
Time taken together = 3 1/3 = 3.33 days
Since we cannot have a fraction of a day, we round it up to the nearest whole day. So, the work will be finished in 3 days.
Therefore, the correct answer is B (3 days).