Question
In a school with 400 students, the average of the age of
the boys is 16 years and that of the girls is 12 years. If the average age of the school is 14 years 9 months. Then the number of girls in the school is.Solution
Let the average age of Boys be ‘x’ According to question, x × 16 + (400 - x) × 12 = 400 × 14(3/4) 16x + 4800 - 12x = 400 × 59/4 4x + 4800 = 5900 4x = 1100 x = 275 Number of girls = 400 - 275 = 125 Alternate Method: By Alligation, Boys Girls 16 12 59/4 59/4 - 12 : 16 - (59/4) 11/4 : 5/4 11 : 5 So Number of girls = 5/(5+11) of 400 = 5/16 of 400 = 125
112, 119, 133, 154, 180, 217
7, 27, 10, 32, 17, 37
99 124 160 209 273 355 454
232, 269, 300, 331, 352, 371
- Find the wrong number in the given number series.
32, 48, 80, 108, 162, 243 1, 1, 3, 15, 105, 942
1001, 934, 863, 790, 711, 630, 539
11 29 45 59 70 81
...18, 27, 38, 56, 66, 83
Find the wrong number in the given number series.
513, 622, 735, 862, 993, 1139
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