Question

b) A certain amount was deposited into a bank account having an interest rate of 5%
of the total amount after 4 years was 1,500. how much was the amount deposited
initially? For the same initial amount how should the interest rate increase such
that the simple interest would amount to 400​

Answer 1

Answer:

$p = 1250 \\ r = 8\%$

Step-by-step explanation:

$let \: p = x \\ r = 5\% \: \: given \\ t = 4years \\ amount = 1500 \\ we \: know \: si = a - p \: \: \: \: or \: \: \: \: 1500 - x \\ si = \frac{p \times r \times t}{100} \\ 1500 - x = \frac{x \times 5 \times 4}{100} \\ 1500 - x = \frac{20x}{100} \\ 1500 - x = \frac{x}{5} \\ (1500 - x) \times 5 = x \\ 7500 - 5x = x \\ 7500 = 6x \\ x = \frac{7500}{6} = 1250 \\ p = x = 1250 \: ans \:$

$now \: for \: second \: part \\ p = 1250 \\ t = 4years \\ \: r = ? \\ si = 400 \\ from \: formula \: \: \: si = \frac{p \times r \times t}{100} \\ r = \frac{si \times 100}{p \times t} \\ = \frac{400\times 100}{1250 \times 4} \\ = \frac{100 \times 100}{1250 } = 8 \\ therefore \: \: r = 8\%$

Answer 2

Answer:

p=1250

r=8%

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