Question
The average of 18 numbers is 70. The first eight
numbers have an average of 90, and the last five numbers have an average of 48. The eleventh number exceeds the tenth number by 20%, and the twelfth number is reduced by (50/9)% from the eleventh number. Determine the value of the eleventh number.Solution
Let tenth number is 10x
So, eleventh number = 1.20 × 10x = 12x
Twelfth number = 850/9 × 1/100 × 12x = 34x/3
So, 10x + 12x + 34x/3
= 70 × 18 – 8 × 90 – 5 × 48
= 1260 – 720 – 240
= 300
Or, 100x/3 = 300
Or, x = 9
So, eleventh number = 12 × 9 = 108
Present ages of P and Q are in the ratio 2:7 respectively. If Q’s age, 15 years hence from now will be 6 times of P’s age, 5 years ago from now, the...
The difference between the compound interest and simple interest on a certain sum for 2 years at 12% per annum is 144. Find the principal amount.
10 years ago, the age of ‘P’ was 50% more than the age of ‘Q’. If the sum of their present ages is 75 years, find the present age of ‘P’.
In three years, the age of person P will be 60% of person Q's age. Currently, person Q is 60% older than person R. Seven years ago, R was 13 years old. ...
Currently, the average age of individuals 'A' and 'B' is 17 years, with 'A' being 2 years older than 'B'. The age of 'C' is 50% greater than that of 'A'...
The ratio of the present ages of father and his son is 5:2. The product of their ages 4 years ago was 31 times of his son’s age that year. What wa...
David’s current age is five years less than one-half of his uncle's present age. After 6 years, his age will be 25% of his uncle’s age. What will Da...
The average age of a father, mother, and daughter is 26 years. The average age of the mother and daughter is twice the age of the daughter. If the ages ...
Five years ago from now, ratio of ages of Aman and Bharat was 3:5, respectively. If 5 years hence from now, ratio of their ages will be 5:7, then find ...
The age of a father is 4 times that of his son. After 6 years, the father will be 3 times as old as his son. Find the present age of the son.
Relevant for Exams:
