NIMCET 2013 — Mathematics PYQ
NIMCET | Mathematics | 2013The sum of the integers between 200 and 400, that are multiples of 7, is:
Choose the correct answer:
- A.
8729
(Correct Answer) - B.
8700
- C.
8972
- D.
8279
8729
Explanation
Solution
To find the sum, we first identify the sequence of multiples of 7 between 200 and 400.
Step 1: Find the first and last terms
-
Dividing 200 by 7: 200÷7=28 with a remainder of 4. The first multiple after 200 is 7×29=203.
-
Dividing 400 by 7: 400÷7=57 with a remainder of 1. The last multiple before 400 is 400−1=399.
So, the sequence is: 203, 210, 217, ..., 399.
This is an Arithmetic Progression (AP) where:
-
First term (a) = 203
-
Last term (l) = 399
-
Common difference (d) = 7
Step 2: Find the number of terms (n)
Using the formula for the nth term:
l=a+(n−1)d
399=203+(n−1)7
399−203=(n−1)7
196=(n−1)7
n−1=7196
n−1=28
n=29
Step 3: Find the sum of the sequence (Sn)
Using the sum formula for an AP:
Sn=2n(a+l)
S29=229(203+399)
S29=229(602)
S29=29×301
S29=8729
Final Answer: The sum is 8729.

