Question
A and B together can complete a task in 40 days, while A
alone takes 100 days to finish it. When A, B, and C work together, they can complete the task in 20 days. Approximately how many days will it take for A and C to complete the task working together?Solution
Let the total work be 200 units
Efficiency of (A + B) = 200/40 = 5 units/day
Efficiency of ‘A’ = 200/100 = 2 units/day
Efficiency of (A + B + C) = 200/20 = 10 units
Therefore, efficiency of (A + C) = Efficiency of (A + B + C) – {efficiency of (A + B) – efficiency of ‘A’}
Or, Efficiency of (A + C) = 10 – (5 – 2) = 7 units/day
Required time taken = 200/7 = 28.57 days ~ 28.5 days
Find the missing number in the given number series.
6, 15, 35, 66, 108, ?11   6   7   12   26    ?    205.5
15, 23, 30, 36, 41, ?
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-5, -2, ?, 10, 19, 30 What will come in place of the question mark (?) in the following series?
36, 85, ?, 230, 330, 451
- What will come in place of (?) in the given number series.
121, 100, 81, 64, ?, 36 7    12    34    117    ?   2465   14820
...Find the missing number in the given number series.
8, 9, 16, 11, 32, 13, ?Find the missing number in the given number series.
442, 424, 410, 400, 394, ?
16, 16, 32, 96, ?, 1920
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