Q:

A) 10 minutes | B) 15 minutes |

C) 12 minutes | D) 20 minutes |

Answer: B) 15 minutes

Explanation:

Explanation:

Working efficiency of both typist together = 100/6 = 16.66%

Let the efficiency of first typist be x and second typist be (16.66 –x)

First typist for 4 minute + second tyoistfor 6 minute = 80% work

⇒4x + (16.66 –x) X 6 = 80%

⇒4x + 100% -6x = 80%,

⇒x = 10%

First typist typed 10% per minute, second typst typed (16.66 –10) = 6.66% per minute

Slowest is second typist complete whole job in 100/6.66 = 15.01 = 15 minute