marcodonzelli wrote:
If 6 coins are tossed, how many different coin sequences will have exactly 3 tails, if all tails have to occur in a row?
A. 4
B. 8
C. 16
D. 20
E. 24
All 3 tails have to occur in a row. We can, thus, count the 3 tails as a single item.
This leaves us with 3 coins that show heads. However, the heads can occur in any position, not necessarily in a row.
Thus, the 3 tails (counted as 1 item) and the 3 heads make for 4 items of which the 3 heads are identical; as shown below:
(T T T), H, H, HThus, total number of arrangements = \(\frac{4!}{3!} = 4\)
Answer A _________________
Sujoy Kumar Datta | GMAT - Q51 & CAT (MBA @ IIM) 99.98 Overall with 99.99 QA
IIT Kharagpur, TUD Germany
LinkedIn:
https://www.linkedin.com/in/sujoy-kumar-datta/Ping me for
GMAT - concepts & strategyDirector - CUBIX (https://www.cubixprep.com) | OneClick (http://www.oneclickprep.com) |
GMAT 100Admissions Consulting: http://www.oneclickprep.com/admissions-consulting/
_________
Email: sujoy.datta@gmail.com,
Skype: sk_datta |
Ask me anything about GMAT