Question

I HAVE ASKED THIS QUESTION LIKE 8 TIMES TODAY AND NO ONE WILL HELP ME:( PLEASE HELP ME I BEG YOU GUYS!!!

A radioactive substance decays at a rate of 2% per day. If there are 50 grams of the
substance left after 34 days, how much was there at the beginning of the 34 days?
Round to two decimal places.

Answer 1

156.25 grams

Explanation:

Well, for starters we know that the substance decays by 2% each day and its been decaying for 34 days. Therefore, the substance has decayed by 68%

34 x 2 = 68

Hence, 50 grams is 32% because the substance has already decayed by 68%

100 - 68 = 32

So now we know 50 grams is 32%. Now we need to find how much 100% is.

50 - 32%

X - 100%

We cross multiply.

50 x 100 = 5000

And divide.

5000 / 32 = 156.25

Thus, in the beginning, there were 156.25 grams in the substance.

Hope this helps! :)