Question

9. The length and breadth of a playground are 75 m 20 cm and 34 m 80 cm
respectively. Find the cost of leveling it at the rate of * 5.50 per square meter. How
long will a boy take to go three times around the field, if he walks at the rate of 1.5
m/sec ?​

Answer 1

Given data : The length and breadth of a ground are 75 m 20 cm and 34 m 80 cm respectively.

To find :

• The cost of leveling it at the rate of Rs 5.50 per square meter.

• How long will a boy take to go three times around the field, if he walks at the rate of 1.5 m/sec ?

Solution : Now, according to given:

⟹ length = 75 m 20 cm = 75.20 m

⟹ breadth = 34 m 80 cm = 34.80 m

{where,

20 cm = 20/100 = 0.2 m

80 cm = 80/100 = 0.8 m }

Let, shape ground be rectangular :

Now,

⟹ Perimeter of rectangular ground

= 2 ( length + breadth )

⟹ Perimeter of rectangular ground

= 2 ( 75.20 + 34.80 )

⟹ Perimeter of rectangular ground

= 2 * 110

⟹ Perimeter of rectangular ground

= 220 m _____( 1 )

Now,

⟹ Area of rectangular ground

= length * breadth

⟹ Area of rectangular ground

= 75.20 * 34.80

⟹ Area of rectangular ground

= 2616.96 m² _____( 2 )

Now,

⟹ cost of leveling = 2616.96 * 5.50

⟹ cost of leveling = Rs 14393.28

Now, by formula, to calculate time taken by boy :

⟹ speed = distance/time

{from eq. ( 1 )}

⟹ 1.5 = 220/time

⟹ time = 220/1.5

⟹ time = 146.67 sec

Time taken by boy to complete three round :

⟹ time = 146.67 * 3

⟹ time = 440.01 sec

Answer : Hence, the cost of leveling the ground at the rate of Rs 5.50 per square meter is Rs 14393.28 and time taken by boy to complete three round of the ground is 440.01 sec.

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