#1**+2 **

We can use complementary counting, and see what are the odds of 0 heads to be up. Since there are 3 coins, and there is a 50% chance to get heads or tails, the odds of having 0 heads is (1/2)^3 = 1 in 8.

Then, subtracting 1/8 from the total probability (8/8), we get **the chance for at least one head to be up as 7/8.**

pryap

proyaop Feb 10, 2022

#2**+2 **

There are 8 possibilities

only ONE ( T T T ) has no 'HEADS'

so 7/ 8 have at leat ONE head

ElectricPavlov Feb 10, 2022