The length and breadth of a rectangle are raised in the proportion 3:4 and 4:5 correspondingly. What is the proportion of the previous place to the new?
Select
A) 2:3
B) 3:5
C) 5:7
D) 7:9
E) None of these
Explanation :   -&gt; If the real length = 3a   And the real breadth = 4a   Area = (3a)*(4a)   =12 a2   -&gt; New Length is 4a and New breadth is 5a   New area is (4a)*(5a)   (3 )*(4 )= 
<gadget id="calculator">(3 )*(4 )</gadget>
<output>12</output>
12 a2   -&gt; New Length is 4a and New breadth is 5a   New area is (4a)*(5a)   = 20 a2   Ratio of previous place to new place  (4 )*(5 )= 
<gadget id="calculator"> (4 )*(5 )</gadget>
<output>20</output>
20 a2   Ratio of previous place to new place= 12 a2 : 20 a2   = 12 : 20   = 3 : 5   Answer : 3:5
<result>B</result>
The length and breadth of a rectangle are raised in the proportion 3:4 and 4:5 correspondingly. What is the proportion of the previous place to the new?