Each step has a rise of
1
4
m and a tread of
1
2
m. (see Fig. 5.8).
Calculate the total volume
of the terrace.
[Hint : Volume of the first step =
6. 150 workers were engaged to finish a piece of work in a certain number of days. Four
workers dropped from the work on the second day. Four workers dropped on third
day and so on. It took 8 more days to finish the work. Find the number of days in which
the work was completed.
[Let the no.of days to finish the work is ‘x’ then
8
150 [2 150 ( 8 1)( 4)]
2
x
x x
+
= ´ + +- - ]
[Ans. x = 17 Þ x + 8 = 17 + 8 = 25]
7. A machine costs ` 5,00,000. If its value depreciates 15% in the first year, 13
1
2
% in the
second year, 12% in the third year and so on. What will be its value at the end of 10
years, when all the percentages will be applied to the original cost?
[Total depreciation = 15 + 13
1
2
+12+....10 terms.
10 S [30 13.5] 82.5%
2
n = -= ]
\ after 10 year original cost =100 - 82.5 = 17.5 i.e., 17.5% of 5,00,000
