MATHS : QUIZ

ANSWERS AND SOLUTION:
1( A)Explanation :7^(x – y) = 343 = 7^3
=> x – y = 3 —————————(Equation 1)
7^(x + y) = 16807 = 7^5
=> x + y = 5 —————————(Equation 2)
(Equation 1)+ (Equation 2) => 2x = 3 + 5 = 8
=> x = 8/2 = 4

2(B)Explanation:
Perimeter = Distance covered in 8 min. = (12000/60x 8)m = 1600 m.
Let length = 3x metres and breadth = 2x metres.
Then, 2(3x + 2x) = 1600 or x = 160.
 Length = 480 m and Breadth = 320 m.
 Area = (480 x 320) m2 = 153600 m^2
3.(C)
4.( D)Explanation:We have: l = 20 ft and lb = 680 sq. ft.
So, b = 34 ft.
Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.
5. (D)
6( C)
7(B)Explanation:
Each day of the week is repeated after 7 days.
So, after 63 days, it will be Monday.
 After 61 days, it will be Saturday.

8(A)Explanation :
Amount of work P can do in 1 day = 1/15
Amount of work Q can do in 1 day = 1/20
Amount of work P and Q can do in 1 day = 1/15 + 1/20 = 7/60
Amount of work P and Q can together do in 4 days = 4 × (7/60) = 7/15
Fraction of work left = 1 – 7/15= 8/15

9(C)Explanation:
Let the average weight of the 59 students be A.
So the total weight of the 59 of them will be 59*A.
The questions states that when the weight of this student who left is added, the total weight of the class = 59A + 45
When this student is also included, the average weight decreases by 0.2 kgs
          59A+45/60 = A-0.2
=> 59A + 45 = 60A – 12
=> 45 + 12 = 60A – 59A
=> A = 57

10( D)Explanation :
Amount of work A can do in 1 day = 1/6
Amount of work B can do in 1 day = 1/8
Amount of work A + B can do in 1 day = 1/6 + 1/8 = 7/24
Amount of work A + B + C can do = 1/3
Amount of work C can do in 1 day = 1/3 – 7/24 = 1/24
work A can do in 1 day: work B can do in 1 day: work C can do in 1 day
= 1/6 : 1/8 : 1/24 = 4 : 3 : 1
Amount to be paid to C = 3200 × (1/8) = 400