Two cross roads, each of width 10 m, cut at right angles through the centre of a rectangular park of length 700 m and breadth 300 m and parallel to its sides. Find the area of the roads. Also find the area of the park excluding cross roads. Give the answer in hectares.

Here, PQ = 10 m and PS = 300 m, EH = 10 m and EF = 700 m
And KL = 10 m and KN = 10 m
Area of roads = Area of PQRS + Area of EFGH – Area of KLMN
[∴ KLMN is taken twice, which is to be subtracted]
= PS x PQ + EF x EH – KL x KN
= (300 x 10) + (700 x 10) – (10 x 10)
= 3000 + 7000 – 100
= 9,900 m²
Area of road in hectares, 1 m² = 1/10000 hectares
∴ 9,900 m² = 9900/10000 = 0.99 hectares
Now, Area of park excluding cross roads
= Area of park – Area of road
= (AB x AD) – 9,900
= (700 x 300) – 9,900
= 2,10,000 – 9,900
= 2,00,100 m²
= 200100/10000 hectares = 20.01 hectares

Class 7 Maths Chapter 11 Exercise 11.4

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