O P Malhotra, S K Gupta and, Anubhuti Gangal Solutions for Exercise 2: Exercise

Calculate the amount and the compound interest by using the formula for compound interest.

Principal             Rate of interest         Time (in years)

$₹625$                    $4\% \mathrm{p}.\mathrm{a}$                     $2$

Calculate the amount and the compound interest by using the formula for compound interest.

Principal             Rate of interest         Time (in years)

$₹8000$                 $15\% \mathrm{p}.\mathrm{a}$                     $3$

Calculate the amount and the compound interest by using the formula for compound interest.

Principal             Rate of interest         Time (in years)

$₹1000$               $10\% \mathrm{p}.\mathrm{a}$                     $3$

Calculate the amount and the compound interest by using the formula for compound interest.

Principal             Rate of interest         Time (in years)

$₹8000$           $10\%$ half-yearly                $1\frac{1}{2}$

Calculate the amount and the compound interest by using the formula for compound interest.

Principal             Rate of interest         Time (in years)

$₹700$              $20\%$ half-yearly              $1\frac{1}{2}$

A district contains $64000$ inhabitants. If the population increases at the rate of $2\frac{1}{2}\%$ per annum, find the number of inhabitants at the end of $3$ years.

The Nagar Palika of a certain city started campaign to kill stray dogs which numbered $1250$ in the city. As a result, the population of stray dogs started decreasing at the rate of $20\%$ per month. Calculate the number of stray dogs in the city three months after the campaign started.

$8000$ blood donors were registered with a charitable hospital. Some student organizations started mobilising people for this noble cause. As a result, the number of donors registered increased at a rate of $20\%$ per half-year. Find the total number of new registrants during $1\frac{1}{2}$ years.