M4maths Previous Puzzles

11 Apr 2013 quadratic

If one root of quadratic equation 3x^2+px+4=0 is 2/3, other root is..

OPtion

1) 2
2) 3/2
3) 4
4) 6
5) 8
6) 4/3
7) 3/4
8) 10
9) 12
10) None of these

Solution

put 2/3 in given equation and find the value of p
and value of p put in given equation
solve the equation and find two roots
one root 2/3 and other 2
option 1

Correct Option: 1 Best Solution (15)

10 Apr 2013 Quadratic equation

If the roots of the quadratic equation x^2-4x-log(base3)a = 0 are real, then least value of "a".....

OPtion

1) 1/9
2) 1/16
3) 1/25
4) 1/36
5) 1/49
6) 1/64
7) 1/81
8) 1/2
9) 1/18
10) None of these

Solution

Given equation are real
Therefore b^2-4ac is >= 0
Solve 16+4log(base3) a >= 0
Ans 1/81
Option 7

Correct Option: 7 Best Solution (7)

09 Apr 2013 Work

The work done by (x+3) labourers in (x-2) days and the work done by (x-2) labourers in (x+5) days are in the ratio 4:5. Value of x is....

OPtion

1) 5
2) 8
3) 10
4) 14
5) 15
6) 16
7) 20
8) 25
9) 28
10) none of these

Solution

Solve

(X+3)*(x-2)/(x-2)*(x+5) is = 4/5

Option 1

Correct Option: 1 Best Solution (7)

08 Apr 2013 Sequence

What is the next number of the following sequence
10, 34, 74, 130, ........

OPtion

1) 147
2) 152
3) 178
4) 202
5) 227
6) 238
7) 252
8) 278
9) 302
10) None of these

Solution

1+9, 9+25, 25+49, 49+81, 81+121
Answer is 81+121 (202)

Correct Option: 4 Best Solution (9)

05 Apr 2013 Find the number

A 2 digit number such that the diff of the number and the number formed by reversing the digit is 9 if diff of the digits is 1 then the number will be

OPtion

1) 21
2) 32
3) 43
4) 54
5) 65
6) 76
7) 87
8) 98
9) all are correct
10) none of obove

Solution

Correct Option: 9 Best Solution (2)

04 Apr 2013 roots

What is the common root of these 4 equations
x^2-11x+18=0
x^2-11x+28=0
x^2-11x+24=0
x^2-11x+30=0

OPtion

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

Solution

roots of the given equations are
9,2
7,4
8,3
6,5

Correct Option: 10 Best Solution (7)

03 Apr 2013 wheel

A wheel makes 2000 revolutions in covering a distance 7.92 km. The Diameter of wheel is....

OPtion

1) .63 m
2) 3.96 m
3) .126 km
4) 12.6 m
5) 1.26 m
6) 1.62 m
7) 2.52 m
8) 1.26 km
9) 2 m
10) None of these

Solution

2000 revolutions = 7.92 km distance cover
1 revolution = 7.92/2000 km
= (7.92*1000)/2000 m
1 revolution = circumference of wheel
circumference of wheel = 792/200 m
therefore 2r = (792*7)/(200*22)
solve
option 5

Correct Option: 5 Best Solution (21)

02 Apr 2013 solve

(100+x)/(101+y) = 1/2 then possible combination for x and y will be
(select your answer out of the 10 given answers)

OPtion

1) 1,101
2) 1,105
3) 7,113
4) 7,121
5) 3,101
6) 3,105
7) 3,139
8) out of given answers exactly two are correct
9) out of given answers exactly three are correct
10) None of these

Solution

200 + 2x = 101 + y
99 + 2x = y (i)
in the given answers
1,101
7,113
3,105
therefore exactly three are correct
option 9

Correct Option: 9 Best Solution (7)

01 Apr 2013 sequence

What is the next no. of the following sequence
5, 13, 25, 41,......

OPtion

1) 49
2) 59
3) 61
4) 64
5) 76
6) 81
7) 100
8) 121
9) 144
10) None of these

Solution

2^2 + 1^2 = 5
3^2 + 2^2 = 13
4^2 + 3^2 = 25
5^2 + 4^2 = 41
6^2 + 5^2 = 61

Correct Option: 3 Best Solution (9)

29 Mar 2013 Triangle

If sides are 7cm, 24cm, 25cm of a triangle. Area of triangle is...

OPtion

1) 75 cm^2
2) 78 cm^2
3) 84 cm^2
4) 96 cm^2
5) 100 m^2
6) 144 cm^2
7) 156 cm^2
8) 164 cm^2
9) 186 cm^2
10) None of these

Solution

In right triangle
Area = 1/2(product of perpendicular sides)
= 1/2(7*24) = 84cm^2
option 3

Correct Option: 3 Best Solution (15)