Question
 In a school with 400 students, the average age of the
boys is 16 years and that of the girls is 12 years. If the average age of school is 14 years 9 months. Then find the number of boys in the school.Solution
Total number of students in school = 400 Let the average age of Boys be ‘x. Then the number of girls in school = 400-x According to the question, x × 16 + (400 - x) × 12 = 400 × 14+9/12 16x + 4800 - 12x = 400 × 59/4 4x + 4800 = 5900 4x = 1100 x = 275 Number of boys = 275
What value should come in place of (?) in the given expression.
450 ÷ 9 + 75% of 160 − 64 ÷ 4 = ?
2/5 of 3/4 of 7/9 of 14400 = ?
7/3 of 4/5 of 15/56 of ? = 83
[564 + 32 of 18 × 9 ÷ 12 + 162 ] ÷ 4 = ?
What should come in place of (?) question mark in the given expression.
 (25% of 320) + (3/8 of 400) − 30 = ?
45% of 360 - 160 + ? = √324
187 ÷ 5 ÷ 0.4 = ? – 24 × 2.4
Find the simplified value of the following expression:
[{12 + (13 × 4 ÷ 2 ÷ 2) × 5 – 8} + 13 of 8]
18 × 15 + 86 – 58 =? + 38
Â
√(24²+285-8²-172) = ?²
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