Question
The average number of novels on historical, thriller and
fantasy in a library is 160, and the average number of novels on historical and fantasy is 155. If the number novels on fantasy is 30% 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 = 160 => x + y + z = 480 ….. (1) And, (x + z)/2 = 155 => x + z = 310 ….. (2) From equation 1 and 2 Number of novels on thriller = y = 170 Number of novels on fantasy = 0.7 × 170 = 119 Therefore, number of novels on historical = 480 – (170 + 119) = 191
What will come in place of (?) question mark in the given number series.
12, 27, 44, 65, ?, 139
124, 107, 91, ? , 62, 49
257, 399, 566, ?, 983, 1237Â
12   18   31   51   ?   112
37, 57, 82, ?, 147, 187
41, 82, ?, 984, 4920, 29520Â Â Â
What will come in place of the question mark (?) in the following series?
4, 3, 7, 26, 101, ?
15, 31, 67, 131, ?, 375
- What will come in place of the question mark (?) in the following series?
121, 115, 102, 82, 55, ? 188    178    158   ?     88    38
