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AMCAT

50514.A polygon has 44 diagonals, then the number of its sides are
11
9
7
5
Explanation:

Let the number of sides be n.
The number of diagonals is given by nC2 - n
Therefore, nC2 - n = 44, n>0
n(n - 1) / 2 - n = 44
n2 - 3n - 88 = 0
n2 -11n + 8n - 88 = 0
n(n - 11) + 8(n - 11) = 0
n = -8 or n = 11.

50515.How many parallelograms will be formed if 7 parallel horizontal lines intersect 6 parallel vertical lines?
42
294
315
None of these
Explanation:

Parallelograms are formed when any two pairs of parallel lines (where each pair is not parallel to the other pair) intersect.
Hence, the given problem can be considered as selecting pairs of lines from the given 2 sets of parallel lines.
Therefore, the total number of parallelograms formed = 7C2 x 6C2 = 315

50516.Ten years ago, Kumar was thrice as old as Sailesh was but 10 years hence, he will be only twice as old. Find Kumar’s present age.
60 years
80 years
70 years
76 years
Explanation:

Let Kumar’s present age be x years and Sailesh’s present age be y years.
Then, according to the first condition,
x - 10 = 3(y - 10) or, x - 3y = - 20 ..(1)
Now. Kumar’s age after 10 years = (x + 10) years
Sailesh’s age after 10 years = (y + 10)
(x + 10) = 2 (y + 10) or, x - 2y = 10 ..(2)
Solving (1) and (2), we get x = 70 and y = 30
Kumar’s age = 70 years and Sailesh’s age = 30 years

50517.A father is twice as old as his son. 20 years ago, the age of the father was 12 times the age of the son. The present age of the father (in years) is
33
44
45
66
Explanation:

Let son’s age = x. Then father’s age = 2x
12 (x - 20) = (2x - 20)
10x = 220
x = 22
Father’s present age = 44 years.

50518.If a^2 + b^2 = c^2, then 1/log c + a^b + 1/logc-a^b =
1
2
-1
-2
Explanation:

logb(c+a) + logb(c-a) =logb(c^2-a^2) = logb b^2 = 2.

50519.If log10 (87.5) = 1.9421, then the number of digits in (875)^10 is?
30
28
33
39
Explanation:

X = (875)^10 = (87.5 x 10)^10
Therefore, log10(X) = 10(log10(87.5 + 1))
= 10(1.9421 + 1)
= 10(2.9421) = 29.421
X = antilog(29.421)
Therefore, number of digits in X = 30.

50520.The cost price of three varieties of oranges namely A, B and C is Rs 20/kg, Rs 40/kg and Rs 50/kg. Find the selling price of one kg of orange in which these three varieties of oranges are mixed in the ratio of 2 : 3 : 5 such that there is a net profit of 20%?
Rs 48
Rs 48.4
Rs 49.2
Rs 49.8
Explanation:

Cost price of one kg of orange in which the three varieties of oranges are mixed in the ratio 2 : 3 : 5 is equal to S where
S = 0.2 x 20 + 0.3 x 40 + 0.5 × 50
= 4 + 12 + 25
= Rs 41
Selling price per kg of oranges to ensure there is a net profit of 20%
= 1.2 x 41
= Rs 49.2

50521.A sweet seller sells 3/5th part of sweets at a profit of 10% and remaining at a loss of 5%. If the total profit is Rs 1500, then what is the total cost price of sweets?
Rs 36,500
Rs 37,000
Rs 37,500
None of these
Explanation:

Assume A be the cost price.
Therefore,
[{(3/5) x A x (10/100)} – {(2/5) x A x 5/100}] = 1500
Or A = Rs 37,500

50522.If 12% of x is equal to 6% of y, then 18% of x will be equal to how much % of y ?
7%
9%
11%
17%
Explanation:

We have ,
12% of X = 6% of Y
=> 2% of X = 1% of Y
=>(2 x 9)% of X = ( 1 x 9)% of Y
Thus, 18% of X = 9% of Y.

50523.If a number is 20% more than the another, how much % is the smaller number less than the first ?
12(1/3)%
16(2/3)%
16(1/3)%
None of these
Explanation:

Take a number 100,
Then the other number is 120
% the smaller number is less than the first = [(20/(120)) x 100]% = 16(2/3)%.

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