Question
In an Aerobic class, the average age of all the members
was 54.5 years, 11 members left the class and 7 new members joined. If the average age increased by 3 years and the total age decreased by 140, what was the number of members in the class initially?Solution
Let the original member be x Total age of these members = 54.5x Total age of (x – 4) members = (54.5x – 140) years According to the question, 54.5x – 140 = (x – 4) × 57.5 ⇒ 54.5x – 140 = 57.5x – 230 ⇒ 57.5x – 54.5x = 230 – 140 ⇒ 3x = 90 x = 30
- 58 83 133 ? 308 433 
- What will come in place of (?) Question mark in the given number series. - 28, 29, 38, 63, 112, 193, ? 
- 6 11 32 111 ? 2345 14100 ...
- 6400, 1600, ?, 80, 16, 4 
- 9 19 39 ? 159 319 
- 8 13 36 123 ? 2585 
- 10, 15, 25, 35, ?, 65 
- What will come in place of the question mark (?) in the following series? - 40, 25, 30, 50, 105, ? 
- 7.5% of 820.68 - 95% of 945.06 + 12.8% of 1050= ? 
- 97, 106, ?, 195, 411, 460