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# Maths Questions for DSSSB Exam :28th June 2018(solutions)

Dear Students!!! There is most general as well as a scoring section in all the competitive entrance examinations in the teaching field i.e “Mathematics”.Because in this section only one thing is work i.e your accuracy and that could be nourished with the daily practice. So, for this, we are providing you the daily quiz for all teaching exams i.e CTET Exam 2018, DSSSB Exam & amp; STET Exams.
Q1. If 16a + 16b = 48, what is the average of a and b?
(a) 2.5
(b) 3.5
(c) 2
(d) 3
Q2. If the average of m numbers is n² and that of n numbers is m², then the average of (m + n) numbers is:
(a) m + n
(b) mn
(c) m/n
(d) m – n
Q3. The average of four numbers A, B, C, D is 40. The average of four numbers A, B, E, F is also 40. Which of the following must be true?
(a) A + B = C + D
(b) A – B = C – D
(c) C + D = E + F
(d) C = E and D = F
Q4. The mean of five numbers is 18. If one number is excluded, their mean is 16. The excluded number is:
(a) 25
(b) 26
(c) 27
(d) 30
Q5. The mean of 100 items was found to be 30. If at the time of calculation, two items were wrongly taken as 32 and 12 instead of 23 and 11, the correct mean is:
(a) 29.4
(b) 29.5
(c) 29.8
(d) 29.9
Q6. The average of 6 numbers is 30. If the average of first four is 25 and that of last three is 35, the fourth number is:
(a) 25
(b) 30
(c) 35
(d) 40
Q7. The average of 100 numbers is 44. The average of these 100 numbers and four other new numbers is 50. The average of the four new numbers will be
(a) 800
(b) 200
(c) 176
(d) 24
Q8. The average of 6 observations is 45.5. If one new observation is added to the previous observations, then the new average becomes 47. The new observation is:
(a) 58
(b) 56
(c) 50
(d) 46
Q9. The average of marks scored by the students of a class is 68. The average of marks of the girls in the class is 80 and that of boys is 60. What is the percentage of boys is the class?
(a) 40%
(b) 60%
(c) 65%
(d) 70%
Q10. The average age of 3 friends is 23. Even if the age of the 4th friend is added, the average remains 23. What is the age of the 4th friend?
(a) 21 years
(b) 23 years
(c) 32 years
(d) cannot be determined
Solutions
S1. Ans.(d)
Sol. 16a + 16b = 48
⇒ 16 (a + b) = 48
⇒ (a + b) = 3
Average of a and b
= (a+b)/2 = 3/2 = 1.5
S2. Ans.(b)
Sol. Total of (m + n) numbers = (mn² + nm²)
= mn (m + n)
Average of (m + n) numbers
= mn (m+n)/(m+n) = mn
S3. Ans.(c)
Sol. (A + B + C + D) = (40 × 4) = 160,
(A + B + E + F) = (40 × 4) = 160
∴ A + B + C + D = A + B + E + F
⇒ C + D = E + F
S4. Ans.(b)
Sol. Total of 5 numbers = (18 × 5) = 90
Total of 4 numbers = (16 × 4) = 64
The excluded number = (90 – 64) = 26
S5. Ans.(d)
Sol. Sum of all the items = (100 × 30) = 3000
Correct sum = (3000 + 23 + 11 – 32 – 12) = 2990
Correct mean = 2990/100 = 29.9
S6. Ans.(a)
Sol. Sum of 6 numbers = (30 × 6) = 180
Sum of first 4 numbers = (25 × 4) = 100
Sum of last three numbers = (35 × 3) = 105
∴ 4th number = (100 + 105 – 180)
= (205 – 180) = 25
S7. Ans.(b)
Sol. Sum of 100 numbers = (44 × 100) = 4400
Sum of 104 numbers = (50 × 104) = 5200
Sum of 4 numbers = (5200 – 4400) = 800
Average of these 4 numbers = 800/4 = 200
S8. Ans.(b)
Sol. Sum of 6 observations = (45.5 × 6) = 273
Sum of 7 observations = (47 × 7) = 329
New observation = (329 – 273) = 56
S9. Ans.(b)
Sol. Let there be x boys and (100 – x) girls.
Then, 60x + 80 (100 – x) = 6800
20x = 1200
⇒ x = 60
Percentage of boys = 60%
S10. Ans.(b)
Sol. Sum of the ages of 3 friends = (23 × 3) = 69 years
Sum of the ages of 4 friends = (23 × 4) = 92 years
Age of the 4th friend = (92 – 69) = 23 years