Let Arnav's age = k yr
Then, Palash's age = 3k yr
Acoording to the question, 3k + 7 = 2(k + 7)

Correct Option: A

Let Arnav's age = k yr
Then, Palash's age = 3k yr
Acoording to the question, 3k + 7 = 2(k + 7)
⇒ 3k + 7 = 2k + 14
⇒ k = 7

∴ Age of Arnav after 14 yr = 7 + 14 = 21 yr
and Palash's present age = 21 yr

Hence, Palash's age is one time of Arnav's age .

Let ages of man and his son are 8k yr and k yr, respectively .
According to the question,
(8k + k)/2 = 27

Correct Option: C

Let ages of man and his son are 8k yr and k yr, respectively .
According to the question,
(8k + k)/2 = 27
⇒ k = (27 x 2)/9 = 6
Hence, age of son after 6 yr = 6 + 6 = 12 yr

When Ravi was born, his mother's age was 26 yr and his elder brother was 3 yr elder to him.
∴ Mother's age when brother was born
= 2 - 3 = 23 yr
Ravi's father was 28 yr of age when his sister was born and his sister was 4 yr of age when his brother was born
∴ Age of father when brother was born
= 28 + 4 = 32 yr

Correct Option: A

When Ravi was born, his mother's age was 26 yr and his elder brother was 3 yr elder to him.
∴ Mother's age when brother was born
= 26 - 3 = 23 yr
Ravi's father was 28 yr of age when his sister was born and his sister was 4 yr of age when his brother was born
∴ Age of father when brother was born
= 28 + 4 = 32 yr

Let us assume the present ages of Mohan and Sohan be 3x years and 4x years;

Correct Option: A

Let us assume the present ages of Mohan and Sohan be 3x years and 4x years; then,
4 Four years ago the ages was 3x - 4 and 4x - 4 years.
According to question, 4 Four years ago the ratio was 5 : 7
( 3x - 4 ) / ( 4x - 4 ) = 5/7
⇒ ( 3x - 4 ) 7 = 5 ( 4x - 4 )
⇒ 21x - 28 = 20x - 20
⇒ 21x - 20x = 28 - 20
∴ x = 8
Hence, their present ages, 3x = 3 x 8 = 24 years; 4x = 4 x 8 = 32 years.
So their present ages 24 and 32 years.

Let son's present age be x years and father's age = (45 - x) years.
∵ (x - 5) (45 - x - 5) = 4 ( 45 - x - 5)
⇒ (40 - x) (x - 9) = 0
⇒ x = 9years

Correct Option: C

Let son's present age be x years and father's age = (45 - x) years.
∵ (x - 5) (45 - x - 5) = 4 ( 45 - x - 5)
⇒ (40 - x) (x - 9) = 0
⇒ x = 9years
∴ The son's age = 9 years
Father's age = 45 - 9 = 36 years