Question

Arnav saves some amount every month. In first three months he saves Rs. 250 , Rs. 300

and Rs. 350 respectively .In which month will he save Rs. 1000​

Answer 1

Given: First month savings =  $Rs. 250$

           Second month savings =  $Rs. 300$

           Third month savings =  $Rs. 350$

To find: The month Arnav will save $Rs. 1000$

Solution: $250, 300, 350...1000$

• Let $a_{1}=250, a_{2}=300, a_{3}=350$

$a_{3}-a_{2}=350-300=50\\ a_{2}-a_{1}=300-250=50$

• Since the difference is same for both, we can say that, this is an AP with $d=50, a=250, a_{n}=1000$

• We need to find $n$ which gives the month Arnav will save $Rs. 1000$ $a_{n}=a+(n-1)d\\ 1000=250+(n-1)50\\ 750=(n-1)50\\ 750=50n-50\\ 800=50n\\ n=16$

Final Answer: Arnav will save $Rs. 1000$ in the 16th month