Average of 20 numbers is 90. Average of first 8 numbers
is 92 while average of last nine numbers is 40. If ninth number is 25% less than the tenth number which is equal to the eleventh numbers then find the tenth number.
A226Correct AnswerIncorrect Answer
B236Correct AnswerIncorrect Answer
C256Correct AnswerIncorrect Answer
D246Correct AnswerIncorrect Answer
Solution
Sum of ninth, tenth and eleventh number = 20 × 90 – 8 × 92 – 9 × 40 = 704 Let tenth number = x = eleventh number So, ninth number = 0.75 × x = 0.75x So, x + 0.75x + x = 704 Or, 2.75x = 704 Or, x = 256
