Three successive discounts of 5%, 15% and 20% equivalent to a single discount is:

Given:

Three successive discounts of 5%, 15%, and 20%

Calculation:

Let the initial value be 100.

Discounted value = (100 – 5)% of (100 – 15)% of (100 – 20)% of 100

⇒ Discounted value = 95% of 85% of 80% of 100

⇒ Discounted value = 95/100 × 85/100 × 80/100 × 100

⇒ Discounted value = 19/20 × 17/20 × 80

⇒ Discounted value = (19 × 17 × 80 ) / 400

⇒ Discounted value = (19 × 17) / 5

⇒ Discounted value = 64.6%

So, single discount percentage = 100 - 64.6 = 35.4%

∴ The correct answer is option (3).