CA Foundation · Quantitative Aptitude · Permutations and Combinations
The value of 10C3 + 10C4 equals which of the following?
The value is 330. Using Pascal's identity, 10C3 + 10C4 = 11C4 = 330. Direct check: 10C3 = 120 and 10C4 = 210, whose sum is 330.
- A330Correct
- B120
- C210
- D462
Explanation
By Pascal's rule, nCr + nC(r+1) = (n+1)C(r+1), so 10C3 + 10C4 = 11C4 = (11×10×9×8)/24 = 330. Check: 120 + 210 = 330. Option 210 is just 10C4, ignoring the addition.
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