Question 1125007
at least 9 heads means 9, 10, or 11 heads
for 11, it is (1/2)^11 or 0.0005
for 10 it is 10*(1/2)^10*(1/2)=0.0049
For 9 it is 55*.5^11 or 0.0269
That sum is the answer or 0.0323