If four distinct positive numbers, a, b, c, and d, in the order given are in proportion, then which of the following options is NOT correct?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. c, d, b, and a, in the order given are in proportion.
When numbers are proportional
a : b :: c : d
a/b = c/d
ad = bc
Now,
Option 1: b/a = d/c ⇒ ad = bc
Option 2: c/d = b/a ⇒ ac = bd [not correct]
Option 3: a/c = b/d ⇒ ad = bc
Option 4: d/c = b/a ⇒ ad = bc
Thus,
c, d, b, and a, in the order given are in proportion.