Option$:(1)$
To figure out how many new products were purchased in $1999.$ We need $2$ pieces of information:-
- How many products were operational at the end of the year $1999$ i.e. $236.$
- How many of the products that were operational at the end of year $1998$ were disposed as junk or products newly purchased in $1997.$
Info $1$ was trivial from the graph itself, for info $2$ we need to do some work as follows:-
We need to find out how many products were newly purchased in $1997$ so that we can get rid of $20\%$ of that amount in $1999.$
In $1997, 10$ products were discarded, $162$ products were operational by the end of the year $1996.$ So, $162-10$ products were operational in the year $1997$ or $152$ products were operational in $1997.$ Now $(182-152)=30$ products were newly bought in the year $1997.$
$20\%$ of $30$ were discarded in $1999$ or $6$ were discarded in $1999. 222-6=216$ products were present in the year $1999$. But operational products given is $236$ so $(236-216)$ or $20$ products were bought.