If you want to test your logic skills and have fun, then read this collection of brain teasers and mind benders and check out how smart you are!!
109. How Many Males?
In a small town of 500000 inhabitants, it has been counted that 42 percent of the males and 28 percent of the females married people from their own town. Assuming these numbers have remained fairly constant over the years, how many males are there in the town?
Answer:
2, 00,000 males.
Method: Assuming also that one man has one wife, then 42/100 of the males = 28/100 of the females
or 42 M = 28 F
or M: F = 28:42
or M: F = 2:3
Therefore two-fifth of the population is male. And so there are 2,00,000 males.
111. Groups of Boys and Girls
In a senior class there are 50 pupils, i.e. 26 boys and 24 girls. The principal decided to divide the pupils into two groups — 30 in Group A and 20 in Group B.
The exact numbers of boys and girls in each group are unknown. The principal knows that the proportion of boys in Group A is larger than that of girls in Group B. How many more boys are there in Group A than girls in Group B?
Answer:
Let, x = number of boys in Group A, and y = number of girls in the same group.
.•. x + y = 30 or y = 30 – x (I)
In group B, the number of girls = 24 – y. So the difference between the boys in Group A and the girls in Group B is:
x – (24–y)
Substituting for y, the expression given in (I) produces:
x – [24– (30 – x)]
Which gives the expression a value of 6. So, there are 6 more boys in group A than girls in group B.
113. Funny Equation
In a classroom of standard VIII somebody wrote an equation on a blackboard; to the left of the equal sign is one symbol, and to the right three symbols. A boy remarks that if the symbol to the left of the equal sign were inverted’ and one of the three symbols to the right were erased, the equation would still be true and contain no redundant or unnecessary symbols. What is the equation? (The line in a fraction counts as a symbol).
Answer:
On the blackboard of standard VII, the following equation must have been written:
6 = SIX
Hint: Inversion of 6 is 9 and symbol ‘S’ is erased, the equation yet becomes true since 9 means IX.
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