The average marks scored by Ram in 5 tests of Physics is 30. How many marks must he obtain in his next test to make the average 32?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 42
An average times the number of tests gives the total marks, so the marks needed in the sixth test are the new total less the old total.
Total of the first 5 tests \(=5\times30=150\)
Total needed for an average of 32 in 6 tests \(=6\times32=192\)
Marks needed in the sixth test \(=192-150=42\)
Shortcut: The sixth test must bring the new average, 32, and also lift each of the 5 earlier tests by 2 marks: \(32+5\times2=42\).