Question

solve this question​

Answer 1

Step-by-step explanation:

length=80m

breadth=35m

Area of playground = l×b

=80×35

=2800m^2

so cost = 2800×4.50

=12600 rs

(ii) speed=1.5 m per second

distance= perimeter of playground

= 2×(80+35)

= 2×115

= 230 m

So,

$time = \frac{distance}{speed}$

$time = \frac{230}{1.5}$

$time = 153.33hrs$

Answer 2

$\bold{\underline{\underline{\huge{\sf{ANSWER:}}}}}$

Given:

The length and breadth of a playground are 80m and 35m respectively.

To find:

• The cost of levelling it at Rs.4.50 per m².'
• A boy take to go three times round the field,if he walks at rate of 1.5m per second.

Explanation:

We have,

• Length of a playground=80m
• Breadth of playground=35m

$\bold{\underline{\huge{Case:1}}}}}}$

Area of playground:

→ Length × Breadth

→ 80m × 35m

→ 2800m²

The cost of levelling it at Rs.4.50/m²

The cost of 2800m² = Rs.[4.50× 2800]

∴ The cost of 2800m² = Rs.12600

$\bold{\underline{\huge{Case:2}}}}}}$

Perimeter of playground= 2(Length + Breadth)

∴Perimeter of playground= 2(80m+35m)

Perimeter of playground= 2(115m)

Perimeter of playground= 230m

Therefore,

A boy take to go thrice round the field:

⇒ 3(perimeter of playground)

⇒ 3× 230m

⇒ 690m

Now,

Speed of boy= 1.5m/second

∴ Time taken by the boy= $\frac{690}{1.5}$

Time taken by the boy= $\frac{690*10}{1.5*10}$

Time taken by the boy=$\frac{\cancel{6900}}{\cancel{15}}=460\:seconds$

If we convert into minutes then time taken by the boy:

We know that 1 minute= 60 seconds

∴ 1 seconds= $\frac{1}{60} \:minutes$

460 seconds= $\frac{460}{60} \:minutes$

$\frac{\cancel{460}}{\cancel{60}} =7.6\:minutes$