Question

If four vertices of a regular octagon are chosen at random, then the probability that the quadrilateral formed by them is a rectangle is

• A. 1/8
• B. 2/21
• C. 1/32
• D. 1/35

Answer 1

Answer: (D)

1/35

Answer 2

Here only 2 rectangles are formed ADEH, GFCB.

∴ Number of favourable cases = 2

and total number of cases = ${ } ^ { 8 } \mathrm { C } _ { 4 }$

∴ Required probability =