Question 83

Sum of all integers lying between 200 and 400 that are multiples of 7 is

Solution

The integers between 200 and 400 divisible by 7 are 203,210...... 399

$$\therefore\ $$Required Sum = 203 + 210 +....+399

$$=7[29+30+.....+57]$$

$$=7[\frac{29}{2}\left(29+57\right)]$$

$$=7[\frac{29}{2}\left(86\right)]$$

$$=7\times29\times43$$

$$=8729$$

Hence, the correct answer is Option D

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