Question

In how many ways can I give Rs. 500 to Y using only Rs. 100 and Rs. 20 notes, with the condition that she has only 16 notes of Rs. 20. and being asked to use the notes of both the denominations.?​

Answer 1

Sum of money is Rs.500

Denominations are Rs.100, Rs.20 notes

No. of Rs.20 notes is 16

To find:

Using both denomination , number of ways X can give Rs.500 to Y.

Explanation:

First, it is needed to find out what sum Rs.20 notes will make,

Rs. 20\times16=Rs.320Rs.20×16=Rs.320

So, if X wanted to use all 16 notes then maximum X can give Rs.320 to Y.

Hence maximum notes that X can use is 15 because 15\times Rs.20=Rs.30015×Rs.20=Rs.300 .

Following are the ways X have for giving Rs.500 to Y

\begin{gathered}5 Rs.20\space notes + 4 Rs.100 notes = 500\\10 Rs.20 notes + 3 Rs.100 notes = 500\\15 Rs.20 notes + 2 Rs.100 notes = 500\end{gathered}5Rs.20 notes+4Rs.100notes=50010Rs.20notes+3Rs.100notes=50015Rs.20notes+2Rs.100notes=500

Answer 2

First, it is needed to find out what sum Rs.20 notes will make,

Rs. 20\times16=Rs.320Rs.20×16=Rs.320

So, if X wanted to use all 16 notes then maximum X can give Rs.320 to Y.

Hence maximum notes that X can use is 15 because 15\times Rs.20=Rs.30015×Rs.20=Rs.300 .

Following are the ways X have for giving Rs.500 to Y

\begin{gathered}5 Rs.20\space notes + 4 Rs.100 notes = 500\\10 Rs.20 notes + 3 Rs.100 notes = 500\\15 Rs.20 notes + 2 Rs.100 notes = 500\end{gathered}

5Rs.20 notes+4Rs.100notes=500

10Rs.20notes+3Rs.100notes=500

15Rs.20notes+2Rs.100notes=500

Hence,there are 3 ways to give Rs. 500 to Y using only Rs. 100 and Rs. 20.