Question

A rectangular field is 72 m by 58 m. Amar walks
round it at the rate of 3 km per hour. What time
will he take in taking 2 rounds.​

Answer 1

AnswEr :

$\bold{Given} \begin{cases} \underline{\scriptsize\sf{A \: Rectangular \: Field \: of \: Dimensions}} \\ \sf{Length=72\:m} \\ \sf{Breadth=58\:m} \\ \sf{Speed \: of \: Walking=3 \: Km/hr}\\ \sf{Time \: Taken \: in \: 2 \: rounds=?}\end{cases}$

• we will calculate Perimeter of Field :

⇒ Perimeter = 2 × (Length + Breadth)

⇒ Perimeter = 2 × (72 m + 58 m)

⇒ Perimeter = 2 × 130 m

⇒ Perimeter = 260 m

• Amar have to complete two rounds :

⇒ Total Distance = 2 × Perimeter

⇒ Total Distance = 2 × 260 m

⇒ Total Distance = 520 m

_________________________________

• Time Taken by Amar is :

⇒ Distance = Speed × Time

⇒ 520 m = 3 Km/hr × Time

⇒ $\sf520 = \cancel3 \times \dfrac{5}{ \cancel{18}}\:m/sec \times Time$

⇒ $\sf520 = \dfrac{5}{6} \times Time$

⇒ $\sf \cancel{520} \times \dfrac{6}{ \cancel5} = Time$

⇒ $\sf104 \times 6 = Time$

⇒ $\sf Time = 624\:sec$

⇒ $\sf Time = \dfrac{624}{60}\:min$

⇒ Time = 10.4 minute

⠀

∴ Amar will Take 10.4 minutes to Round.

Answer 2

Perimeter of field =2(l+b)

=2(72+58)

=260m

He takes 2 round so,

=2*260 = 520m=0.520km.

Speed was 3 km/hr.

Speed =Distance/time

3=0.520/t

t=0.520/3

t= 0.173hr

He need 0.173 hr to cover the distance.