If a:b=2:3, b:c=4:5, then find ratio of a:b:c?

Ans:
        a : b : c
        2   3
             4   5

        a=2*4=8
        b=3*4=12
        c=3*5=15


Ans: 8:12:15


Q & A:

a:b=2:3
b:c=4:5
c:d=6:7

a : b : c : d
2   3
     4   5 
          6   7

a=2*4*6=48
b=3*4*6=72
c=3*5*6=90
d=3*5*7=105

48:72:90:105

If it takes 10 days to die a trench of 100 m long, 50 m broad, 10 m deep, what length of trench, 25 m broad, 15 m deep can be dug in 30 days?

Ans:

       D          L            B            D

      10        100         50           10

      30         x            25           15

     x=100*30*50*10/10*25*15

       = 400m

20 Men-20 Days
25 Men-??days

   =20*20/25
   =16 days


14 Pumps-6 Days
?? Pumps-4 Days

   = 14*6/4
   = 21 days

5 chairs cost as much as 12 stools, 7 stools cost as much as 2 tables, 3 tables cost as much as 2 sofas. If the cost of  5 sofas be Rs. 8750. Find that of a chair.

Ans:
        x rupees=1 chair
        5 chair=12 stools
        7 stools=2 tables
        3 tables=2 sofas
        5 sofas= 8750/-

        x=1*12*2*2*8750/5*7*3*5
          =800/-

Polygons:

Traingles

In right triangle, one angle = 90

and total sum = 180 as in above traingle

A factory produces 470 toy-cars a day. How many cars did it produce in the year 1988, if there are 86 holidays? [Hint: 1988 is a leap year]

Ans: 366-86=280
        =470*280=131600


A factory produces 144 ball-pens in a carton. They have 395 cartons to be filled. They have already made 57000 ball-pens. Do they need to make more ball-pens in order to fill all the cartons?


Ans: 395*144=56880= NO NEED