If 7 spiders make 7 webs in 7 days, then how many days are needed for 1 spider to make 1 web?
Choose the correct choice from the following answers
A) 1
B) 7
C) 3
D) 14
E) 16
Explanation:   Let, 1 spider make 1 web in x days.   More spiders, Less days (Indirect proportion)   More webs, more days (Direct proportion)   Hence we can write as   (spiders)7:1   (webs) 1:7}::x:7   ⇒7×1×7=1×7 × x   ⇒x=7   Answer: Option 7
<result>B</result>
If 7 spiders make 7 webs in 7 days, then how many days are needed for 1 spider to make 1 web?