Question

An element with a mass 310 grams decays by 5.7% per minute. How much of the element is remaining after 9 minutes, to the nearest 10th of a gram

Answer 1

Mass of an element = 310 grams

Percentage of the element that will decay in a minute = 5.7%

Quantity of the element that will decay in one minute :

$= \frac{5.7 \times 310}{100}$

$= \frac{1767}{100}$

$= \tt17.67 \: grams$

Thus, 17.67 grams of the element will decay every minute.

Quantity of element that will decay after nine minutes :

$= 17.67 \times 9$

$=\tt 159.03 \: grams$

Thus, 159.03 grams of the element will decay after 9 minutes.

Quantity of element that will remain after 9 minutes :

$= 310 - 159.03$

$= \tt150.97 \: grams$

Thus, 150.97 grams of the element will remain after nine minutes.

We can round off 150.97 to 151.00.

Therefore, 151.00 grams of the element will remain after 9 minutes.