business mathematics

Puzzles concept

Puzzles:


Introduction:


Puzzles are dealt in a detailed manner with certain solutions.
Different puzzles are gathered from ShakuntalaDevi’s puzzle
books. Keeping in mind certain puzzles for Infosys some
reasoning problems are also dealt. Puzzle name at the top of
each problem will give a brief idea regarding the mode of
application.

SELECTING A CANDIDATE
For an advertisement of six local posts,twelve persons applied
for the job.Can you tell in how many different ways the
selection can be made?

Solution:
6^12

SET OF BAT AND BALL

When I wanted to buy a bat and ball, the shopkeeper said they
would together cost Rs.3.75.But I did not want to buy a ball.
The shopkeeper said that bat would cost 75paise more than the
ball.What was the cost of bat and the ball?

Soluton:
Given that bat and ball together cost Rs.3.75 = 375paise
Let cost of the ball alone be x.
Given cost of the bat is 75p greater than cost of the ball.
So cost of the bat = x+75
x+x+75 = 375
2x = 375 – 75
2x = 300
x = 150p
Hence cost of the ball = Rs.1.50
=>Cost of the bat = 1.50 + 75 = Rs.2.25

PLAYING CHILDREN

A group of boys and girls are playing.15 boys leave.There remain
2 girls for each boy.Then 45 girls leave.There remain 5 boys for
each girl.How many boys were in the orginal group?

Solution:
Let B and G represent no.of boys and girls in the original group
respectively.
G ---------> 2
B-15 ----------> 1
G/B-15 = 2/1
i.e., 2 girls are left for 15 boys who are alone.
G-45 -------------------->1
B-15 ------------------------->5
5 boys are left out when 15 girls are alone.
=>G/B-15=2/1 --------------------------------(1)
=>G-45/B-15 =1/5 ----------------------------(2)
(1) & (2) =>
G = 2B-30
5G – 225 = B - 15
5 ( 2B – 30 ) = B – 15 + 225
10B = B – 15 + 225 + 150
9B = 360
B = 40
(1)=> G/40-15 = 2
G=50 girls.