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.
1
Each step has a rise of m and a tread of
m. (see Fig. 1.8). Calculate the total volume
4
2
of concrete required to build the terrace.
1
[Hint : Volume of concrete required to build the first step = -x + x 50 m']
4 2.
1
m
+50 m
m
4
Fig. 1.8
*
These exercises are not from the examination point of view​

Answer 1

Answer:

Dimensions in 1

st

step = 50×0.25×05 m

Volume of first step =6.25 cubic m

Dimensions of second step= 50×0.5×05m

Volume of 2

nd

step =12.5 cubic m

Dimensions of 3

rd

step = 50×0.75×05 m

Volume of 3

rd

step =18.75 cubic m

Now, we have a=6.25,d=6.25 and n=15

Sum of 15 terms can be calculated as follows:

S

15

=

2

15

[2×6.25+14×6.25]

=

2

15

×100=750

Volume of concrete =750 cubic m