Question

How many number between 1000 and 5000 are exactly divisible by 225

Answer 1

Concept:

Here we will use the formula

$a_{n}=a+(n-1)d$

where, $a_{n}$=$n^{th}$ term of AP

            $a$=$1^{st}$ term of AP

            d= common difference

            n= no. of terms

Given:

a=1125 , $a_{n}$=4950, d= 225,

Find:

We have find no. of terms i.e. 'n'.

Solution:

By using formula,  $a_{n}=a+(n-1)d$

                          4950=1125+(n-1)*225

                          4950-1125=(n-1)*225

                          3825=(n-1)*225

                          3825/225=(n-1)

                          17=(n-1)

                          17+1=n

                           18=n

Hence,  the final number is 18.

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