The sum of all two digit positive numbers which when divided by 7 yiel...
Approach:
To find the sum of all two-digit positive numbers that yield a remainder of 2 or 5 when divided by 7, we need to first find all such numbers and then sum them up.
Finding the numbers:
- The first two-digit number that yields a remainder of 2 when divided by 7 is 16.
- The next number would be 16 + 7 = 23.
- Following this pattern, the numbers that yield a remainder of 2 when divided by 7 are 16, 23, 30, ..., 94.
- The first two-digit number that yields a remainder of 5 when divided by 7 is 19.
- The next number would be 19 + 7 = 26.
- Following this pattern, the numbers that yield a remainder of 5 when divided by 7 are 19, 26, 33, ..., 95.
Calculating the sum:
- We can see that the last number in the first sequence is 94 and in the second sequence is 95.
- To find the sum of all numbers, we can use the formula for the sum of an arithmetic series: Sn = n/2 * [2a + (n-1)d], where a is the first term, n is the number of terms, and d is the common difference.
- For the first sequence: a = 16, d = 7, n = (94-16)/7 + 1 = 14
- For the second sequence: a = 19, d = 7, n = (95-19)/7 + 1 = 14
- Calculating the sum for both sequences and adding them up will give us the final answer.
Therefore, the correct answer is option 'D' 1356.
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