'Anoop, Bittu, Chetan, and Danny' are the four staff

Solution

ATQ, Statement I: Let present age of ‘Anoop’ and ‘Bittu’ is ‘3x’ years and ‘5x’ years, respectively. Present age of ‘Danny’ = ‘7x’ years According to statement, (5x + 5)/(7x + 5) = 3/4 Or, 20x + 20 = 21x + 15 Or, x = 5 Therefore, present age of ‘Danny’ = 7 × 5 = 35 years So, data in statement I alone is sufficient to answer the question. Statement II: Sum of present age of ‘Anoop’, ‘Bittu’, ‘Chetan’ and ‘Danny’ = 24 × 4 = 96 years Sum of present age of ‘Bittu’ and ‘Chetan’ = 23 × 2 = 46 years Since, we cannot find the present age of ‘Danny’. So, data in statement II alone is not sufficient to answer the question. Statement III: Let present age of ‘Danny’ be ‘x’ years. So, Present age of ‘Chetan’ = ‘x + 5’ years And, Present age of ‘Bittu’ = x + 5 – 15 = ‘x – 10’ years And, Present age of ‘Anoop’ = x – 10 – 10 = ‘x – 20’ years According to statement, (x – 20)/x = 3/7 Or, 7x – 140 = 3x Or, x = 35 Therefore, present age of ‘Danny’ = 35 years Statement IV: Let present age of ‘Anoop’, ‘Bittu’, ‘Chetan’ and ‘Danny’ be ‘3x’ years, ‘5x’ years, ‘8x’ years and ‘7x’ years, respectively. Present age of ‘Bittu’ and ‘Chetan’ = 73 – 8 = 65 years So, 5x + 8x = 65 Or, x = 5 Therefore, present age of ‘Danny’ = 7 × 5 = 35 years So, data in statement IV alone is sufficient to answer the question.