ExamBro
ExamBro
MHT CET · Maths · Binomial Theorem

If \({ }^{15} \mathrm{C}_4+{ }^{15} \mathrm{C}_5+{ }^{16} \mathrm{C}_6+{ }^{17} \mathrm{C}_7+{ }^{18} \mathrm{C}_8={ }^{19} \mathrm{C}_{\mathrm{r}}\), then the value of r is equal to

  1. A 9 or 10
  2. B 7 or 12
  3. C 8 or 10
  4. D 8 or 11
Verified Solution

Answer & Solution

Correct Answer

(D) 8 or 11

Step-by-step Solution

Detailed explanation

\({ }^{15} \mathrm{C}_4 + { }^{15} \mathrm{C}_5 = { }^{16} \mathrm{C}_5\) \({ }^{16} \mathrm{C}_5 + { }^{16} \mathrm{C}_6 = { }^{17} \mathrm{C}_6\)