Question
The average number of novels on historical, thriller and
fantasy in a library is 170, and the average number of novels on historical and fantasy is 140. If the number novels on fantasy is 20% less than the number of novels on thriller, then what is the number of novels on historical in the library?Solution
Let the number of novels on historical, thriller and fantasy be x, y and z respectively. Given, (x + y + z)/3 = 170 => x + y + z = 510 ….. (1) And, (x + z)/2 = 140 => x + z = 280 ….. (2) From equation 1 and 2 Number of novels on thriller = y = 230 Number of novels on fantasy = 0.8 × 230 = 184 Therefore, number of novels on historical = 510 – (230 + 184) = 96
What should come in place of (?) question mark in the given number series.
81, 73, 66, 60, 55, ?
14 6 4 4 ? 48
...What should come in place of (?) question mark in the following number series.
5, 11, 23, 47, 95, ?
In each of the following number series, one term is missing. Find the missing term.
1, 4, 9, 16, 25, ?
What will come in place of the question mark (?) in the following series?
4, 11, 32, 95, 284, 851, ?
156, 182, 210, 240, 272, ?
31    32      35      ?      47       56
...What should come in place of (?) question mark in the following number series.
1, 2, 6, 24, 120, ?
What value should come in the place of (?) in the following number series?
71, 72, 76, 103, ?, 244254, ?, 1022, 1150, 1214, 1246
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