NIMCET 2025 — Mathematics PYQ
NIMCET | Mathematics | 2025The number of all even integers between 99 and 999 which are not multiples of 3 and 5 is:
Choose the correct answer:
- A.
240
(Correct Answer) - B.
250
- C.
235
- D.
245
240
Explanation
Solution
Step 1: Define the Range
Integers between 99 and 999 are {100,101,…,998}.
We only need even integers:
S={100,102,104,…,998}
Total number of even integers (n):
998=100+(n−1)2
898=(n−1)2⟹449=n−1⟹n=450
Step 2: Multiples of 3 (within even set)
An even multiple of 3 is a multiple of 6 (2×3).
A={102,108,…,996}
996=102+(nA−1)6
894=(nA−1)6⟹149=nA−1⟹nA=150
Step 3: Multiples of 5 (within even set)
An even multiple of 5 is a multiple of 10 (2×5).
B={100,110,…,990}
990=100+(nB−1)10
890=(nB−1)10⟹89=nB−1⟹nB=90
Step 4: Multiples of both 3 and 5 (within even set)
An even multiple of 15 (3×5) is a multiple of 30 (2×15).
A∩B={120,150,…,990}
990=120+(nA∩B−1)30
870=(nA∩B−1)30⟹29=nA∩B−1⟹nA∩B=30
Step 5: Apply Inclusion-Exclusion Principle
Number of even integers that are multiples of 3 or 5:
n(A∪B)=nA+nB−nA∩B
n(A∪B)=150+90−30=210
Step 6: Required Count
Subtract those that are multiples of 3 or 5 from the total even integers:
Required=Total even−n(A∪B)
Required=450−210=240
Final Answer:
The number of such integers is 240. (Option A)

