Average the price of pencil = ` 2
The price of 30 pens and 75 pencils = ` 510
Let price of a pen = ` p
So, 30 × p+ 75 × 2 = 510
30 p= 510 – 150
p= #360\over30$= 12
So, the price of a pen = ` 12

A alone can complete a work in 18 days and
B alone in 15 days. B alone worked at it for
10 days and then left the work. In how many
more days, will A alone complete the
remaining work ?
(A) 5 days (B) 5$1\over2#
days
(C) 6 days (D) 8 days

Let units of work done by mihir = x
So, the units of work done by topas = 2x
Work completed = 12 days
So, total units of work = (x+ 2x) × 12
= 36x
Time required by Tapas to complete the
work = $36x\over2x$
= 18 day

A sum of money becomes double in 3 years
at compound interest compounded annually.
At the same rate, in how many years will it
become four times of itself ?

At some rate of simple interest, A lent
` 6000 to B for 2 years and ` 1500 to C for
4 years and received ` 900 as interest from
both of them together. The rate of interest
per annum was –