Discussion

If four coins are tossed, then the number of possible ways of getting 2 or 3 heads, is

Answer: B

The number of ways is 10.

Four tosses give \(2^{4} = 16\) equally possible sequences. The number with exactly \(k\) heads is \({}^{4}C_{k}\):

\[ {}^{4}C_{2} + {}^{4}C_{3} = 6 + 4 = 10 \]

For example, the 2-head outcomes are HHTT, HTHT, HTTH, THHT, THTH and TTHH, and the 3-head outcomes are HHHT, HHTH, HTHH and THHH.

6 counts only the two-head case and 4 only the three-head case; 12 and 8 do not correspond to any count of heads.

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