M4maths Previous Puzzles

26 Jun 2011 percentage

40% of 16 + 16% of 40 + 8% of 80 + 80% of 8 + 4 % of 160 + 160% of 4 + 2% of 320 + 320% of 2 is equal to

OPtion

1) 51.2
2) 50
3) 54.6
4) 51
5) 68
6) 68.4
7) 83
8) 81
9) 100
10) none of these

Solution

all are same
so
8* 40*16/100 = 51.2

Correct Option: 1 Best Solution (3)

25 Jun 2011 lcm and hcf

The lcm and hcf of two numbers are 144 and 4. If one of the number is 36 then second number will be

OPtion

1) 8
2) 9
3) 10
4) 12
5) 15
6) 16
7) 18
8) 21
9) 24
10) None of these

Solution

A formula can be used for this question
lcm * hcf = first number * second number
144 * 4 = 36 * x
or x = 16

Correct Option: 6 Best Solution (0)

24 Jun 2011 number

After every hour a number increases 15 % of its present value. How many times it will increase in 8 hours

OPtion

1) 9
2) 8
3) 7
4) 6
5) 5
6) 4
7) 3
8) 2
9) 1
10) None of these

Solution

Let the original number is x
after 15 % increment the new number will be 1.15x
After 8 hour the number will be (1.15^8)x = 3.06x = 3x (approx)
so increase % = (3x-x)*100/x = 200%
so number will increase 2 times

Correct Option: 8 Best Solution (1)

23 Jun 2011 shopkeeper

If a shopkeeper sells an object in 15 % discount, he gets a profit of 30 rupee, but if he sells this object in 20 % discount, he gets a profit of 24 rupee. Printed cost of the object is

OPtion

1) 88
2) 140
3) 120
4) 96
5) 176
6) 230
7) 310
8) 430
9) 84
10) None of these

Solution

Let the printed cost is x rupee.
According to first given condition
original cost for him will be (0.85x-30).
According to second given condition
original cost for him will be (0.80x-24).
On comparing these two values
0.85x-30 = 0.80x-24
or 0.05x = 6 or x = 120

Correct Option: 3 Best Solution (2)

22 Jun 2011 Unit place

What will be the units place of 17^17

OPtion

1) 9
2) 8
3) 7
4) 6
5) 5
6) 4
7) 3
8) 2
9) 1
10) None of these

Solution

17 * 17 * 17 * 17 = 1 in units place
so 17^17 = [17^(4*4)]* 17 = 7 in units place

Correct Option: 3 Best Solution (5)

17 Jun 2011 difference

total minutes between 3:12 PM to 8:46 AM will be

OPtion

1) 956
2) 738
3) 1044
4) 1256
5) 1452
6) 468
7) 386
8) 1126
9) 428
10) none of these

Solution

total difference = 17 hours 34 minutes
= 1020 + 34 min = 1054 min

Correct Option: 10 Best Solution (3)

16 Jun 2011 straight and round

we have to place 8 persons in a 1) straight bench 2) round arrangement.
Difference of the number of methods will be

OPtion

1) 5040
2) 7580
3) 10480
4) 18240
5) 26720
6) 35280
7) 40320
8) 48350
9) 56480
10) none of these

Solution

in straight arrangement total methods = 8*7*6*5*4*3*2*1 = 40320
in round arrangement total methods = 1*7*6*5*4*3*2*1 = 5040
so difference will be 40320 - 5040 = 35280

Correct Option: 6 Best Solution (4)

15 Jun 2011 find the marks of 2 student

The average of marks of physics of 6 students in a class is 68% for makings the overall average of marks of 8 students 73, what should be the total marks of remaining two students (total marks of a subject are 100)

OPtion

1) 167
2) 176
3) 178
4) 164
5) 180
6) 192
7) 168
8) 148
9) 122
10) none of these

Solution

68*6 = 408
73*8 = 584
diff = 176

Correct Option: 2 Best Solution (13)

14 Jun 2011 Fine the number

A positive integer is such that cube of it is equal to the difference of 10 and that integer. The integer will be

OPtion

1) 9
2) 8
3) 7
4) 6
5) 5
6) 4
7) 3
8) 2
9) 1
10) none of these

Solution

by checking method you can solve it easily

x^3 = 10 - x
Only 2 satisfies the above equation

Correct Option: 8 Best Solution (1)

13 Jun 2011 Sum of A and B

6, 11, 106, 121, 206, 231, 306, 341,406, A, B

OPtion

1) 506
2) 451
3) 431
4) 867
5) 967
6) 1001
7) 976
8) 957
9) 876
10) 987

Solution

6+5 = 11
11+(100-5) = 106
106 + 15 = 121
121 + (100-15) = 206
206 +25 = 231
231 + (100-25) = 306
etc

so A = 451
B = 506
A+B = 957

Correct Option: 8 Best Solution (0)