Seven years ago, Prachi was four times as old as her daughter was at that time. Four years from now, Prachi will be two-and-a-half times as old as her daughter would then be. Find the sum of the present ages (in years) of Prachi and her daughter.
69
Given:
Seven years ago, Prachi was four times as old as her daughter was at that time.
Four years from now, Prachi will be two-and-a-half times as old as her daughter would then be.
Let Prachi's present age be P years.
Let her daughter's present age be D years.
Seven years ago, Prachi's age = P − 7
Seven years ago, Daughter's age = D − 7
Given: P − 7 = 4(D − 7)
Four years from now, Prachi's age = P + 4
Four years from now, Daughter's age = D + 4
Given: P + 4 = 2.5(D + 4)
From the first equation:
P − 7 = 4(D − 7)
P − 7 = 4D − 28
P = 4D − 21 (Equation 1)
From the second equation:
P + 4 = 2.5(D + 4)
P + 4 = 2.5D + 10
P = 2.5D + 6 (Equation 2)
Equating Equation 1 and Equation 2:
4D − 21 = 2.5D + 6
Equating Equation 1 and Equation 2:
4D − 21 = 2.5D + 6
⇒ 4D − 2.5D = 6 + 21
⇒ 1.5D = 27
⇒ D = 18
Substitute D = 18 in Equation 1:
P = 4(18) − 21
⇒ P = 72 − 21
⇒ P = 51
Sum of the present ages of Prachi and her daughter:
P + D = 51 + 18
⇒ P + D = 69
The sum of the present ages of Prachi and her daughter is 69 years.
One year ago, the age of B was twice that of A. After 9 years, if the ratio of the ages of B and A would be 4 : 3, then the sum of their present ages is ____ years.
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The ratio of the ages of A, B and C, 5 years ago, was 4 : 5 : 7. The sum of their present ages is 135 years. What will be the sum of the ages (in years) of B and C, 3 years from now?
The ratio of the present age of Mahesh and Ajay is 3 : 2 respectively. After 8 years. Ratio of their age will be 11: 8. What will be the present age of Mahesh’s son if his age is half of the present age of Ajay?
In a school, the average age of boys and girls together is 16.8 years, the average age of boys is 15.4 years, and the average age of girls is 18.2 years. The ratio of number of boys to girls in the school is:
The difference between age of Sunita and Sheela is 12 years. If 9 years ago, elder's age was 4 times of younger's age, then what are their present age?
A. 11 and 23
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C. 13 and 25
D. 23 and 35