Question

A boy saves rs 1 in first day rs 2 on second day and rs 4 on third day and so on how much did the boy save upto 20 days?

Answer 1

Answer:

105

Step-by-step explanation:

(1+20)*5=105

so

we will get 105

(21*5)

Answer 2

$\large \bigstar\boxed{\bf \red{ GIVEN}} \bigstar \\ \Longrightarrow \bf a = 1 \\ \\\Longrightarrow \bf r = \frac{2}{1} = 2 \\ \\ \Longrightarrow \bf n = 20$

$\large \bigstar\boxed{\bf \red{TO \: FIND }} \bigstar\\ \\\Longrightarrow \bf Total \: saving \: after \: 20 \: days$

$\large \bigstar\boxed{\bf \red{SOLUTION}} \bigstar \\ \\ \bf By \: using \: G.P. \: formula : \\ \\ \large \boxed{ \bf \blue{ {a}_{n} = {ar}^{n - 1} }} \\ \\ \bf {a}_{n} = 1 \times ( {2})^{20 - 1} \\ \\ \bf {a}_{n} = {2}^{19} \\ \\ \large \boxed{ \orange{ \bf {a}_{n} = 524288}}$

Boy saves 524288 Rs in 20 days