Timed Quant Medium Section 2 Test #3 Q9

GRE Quant Problem Solving
1

The questions reads: “Julia flips a coin three times. What is the probability she receives at least one head and one tails?”

In his solution Mr. Greg says the possibilities are “HHT” and “HTT”. However, if the question ask for the probably of “one tails” then only the first outcome “HHT” satisfies that right, since the second outcome has two tails. The set “HHT” and “HTT” would be the outcomes for at least one heads and at least one tails right? Or is that what the question is in fact asking and i understood it wrong?

2

“at least one head and one tails” would be grammatically incorrect. Assuming you mean “at least one head and one tail,” then the scope of the modification suggests that “at least” applies to both the head and the tail.

To avoid ambiguity, you could remove the second “one” or change it to “a”, depending on what you want to express:

  1. “at least one head and tail” → At least one head + at least one tail

  2. “at least one head and a tail” → At least one head + singular tail (though this is still open to ambiguity)