question in the picture below

The doubling time after 4 and 7 years is 400 months and 700 months respectively
The formula for finding doubling time is given as;
Doubling time = [tex]t \frac{In 2}{In 1 + \frac{r}{100} }[/tex]
Where t = time = 4 and 7 years
r = rate
For 4 years, we have
Doubling time = [tex]4 * \frac{In 2}{In ( 1 + \frac{0.7}{100}) }[/tex]
⇒ [tex]4 * \frac{In 2}{In 1. 0074}[/tex]
⇒ [tex]4 * \frac{0. 6931}{0. 0074}[/tex]
⇒ [tex]4[/tex] × [tex]93. 66[/tex]
⇒ 374. 65
⇒ 400 months in the nearest hundredth
For 7 years
⇒ [tex]7[/tex] × [tex]93. 66[/tex]
⇒ [tex]655. 62[/tex]
⇒ 700 months in the nearest hundredth
Thus, the doubling time after 4 and 7 years is 400 months and 700 months respectively
Learn more about doubling time here:
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