Answer: Option C
Let the required number days be x.
Less spiders, More days (Indirect Proportion)
Less webs, Less days (Direct Proportion)
1 x 7 x x = 7 x 1 x 7
x = 7.
Answer: Option B
Let the required number of revolutions made by larger wheel be x.
Then, More cogs, Less revolutions (Indirect Proportion)
14 : 6 :: 21 : x 14 x x = 6 x 21
x = 9.
Let the required number of days be x.
Less cows, More days (Indirect Proportion)
Less bags, Less days (Direct Proportion)
1 x 40 x x = 40 x 1 x 40
x = 40.
Answer: Option A
Let the required weight be x kg.
Less weight, Less cost (Direct Proportion)
250 : 200 :: 60 : x 250 x x = (200 x 60)
x = 48.
x = 6.