JAMB Mathematics 2020 Objective — Question 8
Question 8 of 40 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2020 Objective paper, with the correct answer and a full explanation.
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7 pupils of average age 12years leave a class of 25 pupils of average age 14years. If 6 new pupils of average age 11years join the class, what is the average age of the pupils now in the class?
- A. 11yrs
- B. 13yrs, 10monthsCorrect
- C. 13yrs, 5months
- D. 13yrs
Explanation
Sum of ages of 25 pupils = 25x14=350 years. Sum of ages of 7 leaving pupils = 7x12=84 years. Remaining 18 pupils' sum = 350-84=266 years. Sum of ages of 6 new pupils = 6x11=66 years. Total for 24 pupils = 266+66=332 years. Average = 332/24 = 13.833 years = 13yrs, 10months.
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