Six years ago, A was four times as old as B. Six years

Q: Answer-Six years ago, A was four times as old as B. Six years from now, A will be twice as old as B. Find t...

Let present ages be A years and B years. Six years ago A 6 4B 6 ...1 Six years hence A 6 2B 6 ...2 Expand 1 A 6 4B 24 A 4B 18 ...i Expand 2 A 6 2B 12 A 2B 6 ...ii Subtract i from ii A 2B A 4B 6 18 2B 4B 24 2B 24 B 12 From ii A 2 12 6 A 24 6 A 30 Answer Present ages A 30 years B 12 years.

from now, A will be twice as old as B. Find their present ages.

A A = 50 years; B = 12 years. Correct Answer Incorrect Answer

B A = 30 years; B = 12 years. Correct Answer Incorrect Answer

C A = 30 years; B = 22 years. Correct Answer Incorrect Answer

D A = 20 years; B = 12 years. Correct Answer Incorrect Answer

Solution

Let present ages be A years and B years. Six years ago: A − 6 = 4(B − 6) ...(1) Six years hence: A + 6 = 2(B + 6) ...(2) Expand (1): A − 6 = 4B − 24 A − 4B = −18 ...(i) Expand (2): A + 6 = 2B + 12 A − 2B = 6 ...(ii) Subtract (i) from (ii): (A − 2B) − (A − 4B) = 6 − (−18) −2B + 4B = 24 2B = 24 ⇒ B = 12 From (ii): A − 2 × 12 = 6 A − 24 = 6 ⇒ A = 30 Answer: Present ages: A = 30 years; B = 12 years.

Practice Next

Relevant for Exams:

DRDO Senior Technical Assistant

Thank You for posting your query. Please check your email for further guidance

Please Register/Login to Download Question