Question

In a geometric series each term is 21% less than previous term what is the value of r for this geometric series

Answer 1

Answer:  The required common ratio is 0.79.

Step-by-step explanation:  Given that in a geometric series, each term is 21% less than the previous term.

We are to find the common ratio r for this geometric series.

Let the first term of the give geometric series be a.

Then, according to the given information, the second term of the geometric series will be

$a_2=a-21\%\times a=a-\dfrac{21}{100}a=\dfrac{100-21}{100}a=\dfrac{79}{100}a=0.79a.$

Therefore, the required common ratio for the given geometric series is given by

$r=\dfrac{0.79a}{a}=0.79.$

Thus, the required common ratio is 0.79.

Answer 2

To get a number to decrease by 21% you multiply it by 0.79 (1-0.21)
r = 0.79