Question

Question 5 A small terrace at a football ground comprises of 15 steps each of which is 50 m long and built of solid concrete. Each step has a rise of m and a tread of m (See figure) calculate the total volume of concrete required to build the terrace.

Class 10 - Math - Arithmetic Progressions Page 115

Answer 1

Sum of n terms of an AP

The sum of first n terms of an AP with first term 'a' and common difference 'd' is given by

Sn = n /2 [ 2a + ( n - 1) d] or
Sn=n /2 [ a + l ]       (l = last term)-----------------------------------------------------------------------------------------------------

 volume of cuboid = l ×b×h 

[ solution & figure is in the attachment]

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Hence, the total volume of concrete required to build the terrace is 750
 
m³

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Hope this will help you.....

Answer 2

hope it helps you be happy