Question

A Scientist has 1200 grams of radioactive substance. Every day, half of the substance decays and only half remains.on which day will the scientist have less than one gram of the substance left ? There will be less than one gram on day ________

Answer 1

Explanation:

Day 1: 1200g / 2¹ = 600g

Day 2: 1200g / 2² = 300g

Day 3: 1200g / 2³ = 150g

The pattern is the amount of radioactive substance on day n is 1200 / (2^n).

Therefore, we have to find n where 2^n > 1200.

The first such n is 11 (2¹¹ = 2048).

Hence, there will be less than 1 gram on day 11.