Answer
$\frac{1}{2}$
Work Step by Step
P(E) = $\frac{no.\ of\ outcomes\ in\ favor}{Total\ no.\ of\ outcomes}$
Given that H is heads and T is tails, the set of equally likely outcomes is:
S = {HH, HT, TH, TT}.
E: Different outcomes on each toss.
Favorable outcomes= {HT, TH}
P(E) = $\frac{2}{4}$ = $\frac{1}{2}$