7 pupils of average age 12 years leave a class of 25 pupils of average age 14 years. If 6 new pupils of average age 11years join the class, what is the average age of the pupils now in the class?
A. 13years B. 12 years 7\(\frac{1}{2}\) months C. 13 years 5 months D. 13 years 10 months E. 11 years
Correct Answer: D
Explanation
Total age of the 7 pupils = 7 x 12 = 84 Total age of the 25 pupils = 25 x 14 = 350 Total age of the 6 pupils = 6 x 11 = 66 7 pupils leaving a class of 25 pupils given 18 pupils Total age of the 18 pupils = 350 - 84 = 266 6 pupils joining 18 pupils = 24 Total age of 24 pupils = 266 + 66 = 332 Average age of 24 pupils now in class \(\frac{332}{24}\) = 13yrs 10 months
