32.
If 17 labourers can dig a ditch 20 m long in 18 days, working 8 hours a day;
how many more labourers should be engaged to dig a similar ditch 39 m long in 6
days, ech labourer working 9 hours a day?
[A]
34
[C]
68
[B]
51
[D]
85
Answer : B
Explanation :
|
Let
the total number of men to be engaged be x.
|
|
More
length, More labourers (Direct Proportion)
|
|
Less
days, More labourers (Indirect Proportion)
|
|
More
hours per day, Less labourers (Indirect Proportion)
|
|
|
|
|
Length
|
26
: 39
|
Days
|
6
: 18
|
Hours
per day
|
9
: 8
|
|
|
::
17 : x
|
|
|
|
|
|
|
|
|
(26
x 6 x 9 x x) = (39 x 18 x 8 x 17)
|
|
|
|
|
|
|
x
=
|
(39 x 18 x 8 x 17)
|
(26 x 6 x 9)
|
|
=
68
|
|
|
|
|
|
Number
of more labourers = (68 - 17) = 51
|
|
|
