2) Comparative scale is a pair of scale having a common

Answer is:

representative fraction

RRB JE Mechanical Question Paper 2014 (Set-3) with Answer Key

3) A tap can fill a tank in 16 minutes and another can empty it in 8 minutes. If the tank is already half full and both the taps are opened together, the tank will be

Answer is:

emptied in 8 minutes

Explanation:

If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours (where x > y), then on opening both the pipes, the net part emptied in 1 hour = (1/y)-(1/x)
= (1/8 - 1/16) = 1/16
Time taken to empty the full tank = 16 min.
Hence, time taken to empty the half tank = 8 min