This document describes the rules and structure of a mental math competition consisting of 5 rounds. It provides sample questions and answers for each round, with the rounds getting more difficult. The competition involves teams answering math problems within time limits, with points awarded for correct answers and deducted for incorrect ones. Teams can optionally pass questions to other teams in some rounds. The final round involves answering multiple questions at once within a time limit.

1. MENTAL MATHS
CLASS 9

2. Round 1
Rules-
1.One question per team.
2.Every team will be given 30 seconds to answer.
3.Correct answer will be given 10 points.
4.No negative marking.
5.Questions cannot be passed in this round

4. If ‘+’ means ‘÷’, ‘–’ means ‘×’, ‘÷’ means ‘+’
and ‘×’ means ‘–’, then
320 ÷ 225 + 15 × 15 – 85 = ?
1
A. B.
C. D.
180
-940
780
-140

5. If ‘+’ means ‘÷’, ‘–’ means ‘×’, ‘÷’ means ‘+’
and ‘×’ means ‘–’, then
320 ÷ 225 + 15 × 15 – 85 = ?
1
A. B.
C. D.
180
-940
780
-140

7. Probability of an event can be ?
2
A. B.
C. D.
–0.7
0.6
1.001
11
9

8. Probability of an event can be ?
2
A. B.
C. D. –0.7
0.6
1.001
11
9

10. The ratio of girls: boys in a school is
5:7. If there are 525 girls, how many
boys are there?
3
A. B.
C. D.
335
435
735
635

11. The ratio of girls: boys in a school is
5:7. If there are 525 girls, how many
boys are there?
3
A. B.
C. D.
335
435
735
635

13. Find the missing number 2,8,18,32,?
4
A. B.
C. D.
62
46
50
60

14. Find the missing number 2,8,18,32,?
4
A. B.
C. D.
62
46
50
60

16. AUDIENCE QUESTION

17. AUDIENCE QUESTION
2

18. Round 2
Rules-
1.Two question per team.
2.Every team will be given 45 seconds to
answer.
3.Correct answer will be given 10 points.
4.Wrong answer will be given -5 points.
5.You can pass the question to another team
6.Pass question will be given 5 points.
7.Question will be passed only once.

20. 70
135
39
23
1 Find the wrong term 9, 11, 15, 23, 39, 70, 135

21. 70
135
39
23
1 Find the wrong term 9, 11, 15, 23, 39, 70, 135

23. 11/5
5/11
5/3
3/5
2 If 2x-3y +4x-7y=0, then the value of y/x is:

24. 11/5
5/11
5/3
3/5
2 If 2x-3y +4x-7y=0, then the value of y/x is:

26. 200%
250%
150%
160%
3 A is 40% of B. What percentage is B of A?

27. 200%
250%
150%
160%
3 A is 40% of B. What percentage is B of A?

29. Decreased by 8%
Increased by 8%
Decreased by 4%
Increased by 4%
4 The price of an item increases by 20% and then
decreases by 20%. So the price has:

30. Decreased by 0%
Increased by 0%
Decreased by 4%
Increased by 4%
4 The price of an item increases by 20% and then
decreases by 20%. So the price has:

32. 22
20
23
19
5 If 2x+5y=18 and x=2, what is the value of 4x+5y:

33. 22
20
23
19
5 If 2x+5y=18 and x=2, what is the value of 4x+5y:

35. 48
40
36
32
6 A person’s present age is two-fifth of the age of
his mother. After 8 years, he will be half of the
age of his mother. How old is the mother at
present ?

36. 48
40
36
32
6 A person’s present age is two-fifth of the age of
his mother. After 8 years, he will be half of the
age of his mother. How old is the mother at
present ?

38. 14:11
22:7
11:7
4:1
7 The perimeter of a circle is equal to the
perimeter of a square. Then, the ratio of their
areas respectively, is

39. 14:11
22:7
11:7
4:1
7 The perimeter of a circle is equal to the
perimeter of a square. Then, the ratio of their
areas respectively, is

41. 50 years
45 years
25 years
30 years
8 15 years ago, Kanika's father was five times as
old as Kanika. After 15 years, her father will be
thrice as old as her. The present age of Kanika
is

42. 50 years
45 years
25 years
30 years
8 15 years ago, Kanika's father was five times as
old as Kanika. After 15 years, her father will be
thrice as old as her. The present age of Kanika
is

44. Audience Question
Count the number of squares in the figure.

45. AUDIENCE QUESTION
30

46. Round 3
Rules-
1.Two question per team.
2.Every team will be given 60 seconds to answer.
3.Correct answer will be given 10 points.
4.Wrong answer will be given -5 points.
5.No pass questions allowed.

48. 1.

49. Answer
3

51. 2. Find the missing number

52. Answer
36

54. 3. Find the missing number

55. Answer
1

57. 4. In a garden, 40% of the flowers are roses,
30% are lilies, and the rest are daisies. If
there are 150 daisies, how many flowers are
there in total?

58. Answer
500
flowers

60. 5. A can do a piece of work in 10 days , and B
can do the same work in 20 days . With the
help of C , they finished the work in 4 days .
C can do the work in how many days,
working alone ?

61. Answer
10 Days

63. 6. A and B can do a piece of work
in 5 days, B and C can do it in 7 days. A and C can
do it in 4 days. Who among these will take the
least time if put to do it alone ?

64. Answer
A

66. 7. A man wants to reach a window which is 40ft.
above the ground. The distance from the foot of
the ladder to the wall is 9 feet. How long should
the ladder be?.

67. Answer
41 feet

69. 8. A train is one mile long. It travels at the rate of
one mile a minute through a tunnel which is also
one mile long. Can you say how long it will take
for the train to pass completely through the
tunnel?.

70. Answer
2 minute

72. Round 4
Rules-
1.One question per team.
2.Every team will be given 60 seconds to answer.
3.Correct answer will be given 10 points.
4.Wrong answer will be given -5 points.
5.No pass questions allowed.

73. 1. An aeroplane files twice is fast than a train
which covers 60 miles in 80 minutes. What
distance will the aeroplane cover in 20 minutes?

74. Answer
30 miles

76. 2. There is a number which is very peculiar. This
number is three times the sum of its digits. Can
you find the number?.

77. Answer
27

79. 2. There is a number which is very peculiar. This
number is three times the sum of its digits. Can
you find the number?.

80. Answer
27

82. 3. A rational number is such that when you
multiply it by 5/2 and add 2/3 to the product,
you get -7/12. What is the number?

83. Answer
-1/2

85. 1.4. Find the measure of an interior angle of a
regular polygon of 9 sides.

86. Answer
140

88. Round 5
Rules-
1.Seven question per team.
2.Every team will be given 100 seconds to answer as
many as possible.
3.All questions will be displayed at once.
4.You many answer in any random order.
5.Correct answer will be given 10 points.
6.No negative marking.

89. 1. A hollow pipe is 21cm long and its external diameter is 8cm. If
the thickness of the pipe is 1cm, then find the volume of the
pipe
2. How many lead balls, each of radius 2cm can be made from a
solid sphere of radius 16cm?
3. A coin is tossed successively three times. Find the probability
of getting exactly one head or two heads.
4. If 2×3=812, 4×5=1620 then 6×7=?
5. If Monday is to February, then Friday is to ?
6. What is the missing number in the series: 2, 5, 10, 17, ?, 37
7. In a marathon race, John finishes 20 seconds ahead of Jack. If
John's average speed is 15 km/h and Jack's average speed is 12
km/h, what is the length of the race?

90. 1. 462 cu cm
2. 512
3. ¾
4. 2428
5. June
6. 26
7. 4km

92. 1. If the total surface area of a solid hemisphere is 462 sq.m, find its
curved surface area.
2. If the capacity of a cylindrical tank is 1848 cum and its base
diameter is 14m,then find the depth of the tank.
3. A bag contains 6 red balls and some white balls. If the
probability of drawing a white ball is double that of a red ball.
find the number of white balls in the bag.
4. 33x-2 = 92x-2 find x.
5. Find the sum of first 20 odd natural numbers.
6. If 3 workers can complete a project in 10 days, how many
workers are needed to complete the project in 5 days?
7. The sum of the interior angles of a polygon is 1620 degrees. How
many sides does the polygon have?

93. 1. 308 sq cm
2. 12 m
3. 12
4. 2
5. 400
6. 6 workers
7. 10 sides

95. 1. If the volumes of two cones are in the ratio 1:4 and their diameters are
in the ratio 4:5, find the ratio of their heights.
2. The radii of the bases of a cylinder and a cone are in the ratio 3:4 and
their heights are in the ratio 2:3, find the ratio of their volumes.
3. A card is drawn from a well shuffled deck of 52 cards. Find the
probability that the card drawn will be neither a king nor a queen
4. 2x-3y=5 and xy=4 Find 4𝑥2
+9𝑦2
.
5. 1/3 : 1/4 ::20x : ?
6. If a number is increased by 15% and then decreased by 10%, what is
the net percentage change?
7. The sum of two consecutive odd numbers is 104. What are the two
numbers?

96. 1. 25:64
2. 9:8
3. 11/13
4. 73
5. 15x
6. 4.5% increase
7. 51 and 53

98. 1. If each side of a cube is decreased by 25%, then find the ratio of volumes of
original cube and the resulting new cube.
2. Garvit was making a mathematical model, in which he placed 4 cubes each
of edge 20cm one above the other. Find the surface area of resulting
cuboid.
3. A card is drawn from a well shuffled deck of 52 cards. Find the probability
that the card drawn will be either a red card or a black face card
4. 48, 45, 40, 33, 24 ......, ......
5. Point ‘A’ is located 8 km South of B and C is located 6 km West of A. what
is the distance between C and B?
6. A number, when divided by 5, leaves a remainder of 3. When the same
number is divided by 7, it leaves a remainder of 4. What is the smallest
possible value of the number?
7. If March is to August, then C is to

99. 1. 64:27
2. 7200 sq cm
3. 8/13
4. 13,10
5. 10km
6. 18
7.H

100. TIE BREAKER
A container contains a mixture of milk and
water in the ratio of 5:3. If 15 liters of the
mixture is replaced with pure milk, and
then 10 liters of the new mixture is replaced
with pure water, the final mixture has a
ratio of milk to water as 4:3. Let the initial
quantity of the mixture in the container is
a/b. What is value of a & b

101. a = 40 and b =3