We know that
• The probability of a head is 1/2.
,
• The probability of a tail is 1/2.
Notice that the number of times they flip a coin is 7. Since both probabilities are the same, we just have to multiply 1/2 seven times by itself.
Now, we multiply the probability with 7 since there are 7 possibilities.
Then, we multiply by 100 to express it as a percentage.
Therefore, the answer is C. 5.5%.