MATH QUESTIONS AND ANSWERS FOR GRADE 7

Question 1 :

The temperature at 12 noon was 10° C above zero.If it decreases at the rate of 2°C per hour until midnight, at what time would the temperature be 8°C below zero? 

(A)   3 pm       (B)  9 pm        (C)  8 pm

Solution :

Temperature at 12 noon  =  10° C

Decreasing rate =  2°C per hour

Total fall of temperature from 10° C to 0° C and 0° C to 8° C  =  -10 - 8  =  -18

Time taken  =  -18/2  =  9 hours

At 9 pm the temperature will be 8°C below zero.

Question 2 :

An elevator decends into a mine shaft at the rate of 6 m/min.If the decline starts from 10 m above the ground level. Calculate how long will it take to reach -350 m ?

(A)  1 hour            (B)  5 hours             (C)  2 hours 

Solution :

Starting position of mine shaft is 10 m above the ground but it moves in opposite direction.

So, it travels the distance (–350) m below the ground.

The total distance covered by mine shaft

= 10 m – (–350) m = 10 + 350 = 360 m

Now, time taken to cover a distance of 6 m by it

=  (1/6) minute

Time taken to cover a distance of 360 m  =  (1/6) ⋅ 360

60 minutes = 1 hour

Thus, in one hour the mine shaft reaches –350 below the ground.

Question 3 :

How much less is 28 km than 46.2 km?  

(A)  18.2 km     (B)  14.6 km     (C)  12.5 km

Solution :

In order to find 28 km is how much less than 46.2 km, we have to perform subtraction.

46.2 -  28  =  18.2 km

Question 4 :

Solve 5p + 2 = 17 

(A)   p = 2        (B) p = 5         (C)  p = 3

Solution :

5p + 2 = 17 

Subtract both sides by 2

5p  =  17 - 2

5 p = 15

Divide both sides by 5

p =  15/5  =  3

So, the value of p is 3.

Question 5 :

When two lines l and m meet, we say they intersect, the meeting point is called the __________________

(A) Point of contact   

(B) Point of intersection

(C)  None of these

Solution :

The meeting point of two lines is called the point of intersection.

Question 6 :

Find the value of x in the following triangle

(A)   50°    (B)   70°   (C)   80°

Solution :

In a triangle, an exterior angle is equal to the sum of the interior opposite angles

x  =  <ABC + <ACB

x =  30 + 40

x  =  70°

Question 7 :

The population of a city reduced from 25,000 to 24,500. Find the percentage decrease.

(A)   5%        (B)  2%             (C)  1%

Solution :

Original population  =  25000

Reduced population  =  24500

Difference between old and new population 

=  25000 - 24500

  =  500

Decrease percentage  =  (500 / 25000) ⋅ 100

=  2%

Question 8 :

A wire is in the shape of square of side 10 cm. If the wire is rebent in to a rectangle length 12 cm, calculate its width.

(A)   35%       (B)   27%      (C)  75%

Solution :

Perimeter of square  =  Perimeter of rectangle 

Side length of square a = 10 cm

4a  =  4 (10)  =  40

Perimeter of rectangle  =  40

2 (l + w)  =  40

2(12 + w)  =  40

12 + w =  20

Subtract both sides by 12

w  =  20 - 12  =  8 cm

Hence the width of rectangle is 8 cm.

Question 9 :

Two sides of a parallelogram ABCD are 6cm and 4cm. The height corresponding to the base of CD is 3 cm. Find the area of the parallelogram

(A)  7 cm²           (B)   15 cm²             (C)   18 cm²

Solution :

Area of parallelogram  ABCD  =  Base ⋅ Height

Area of parallelogram ABCD  =  6(3)  

  =  18 cm²

Question 10 :

Diameter of a circular garden is 9.8 m. Calculate its area. 

(A)  50 cm       (B)  64 cm      (C)   30 cm

Solution :

Diameter of circular garden  =  9.8 m

r =  9.8/2  =  4.9

Area of circular garden  =  πr²

  =  (22/7) (4.9)² 

  =  75.46 m²

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