Suppose an unfair coin comes up tails 38.9% of the time if it is flipped. If the coin is flipped 12 times, what is the probability that:
a) it comes up heads exactly 7 times?
b) it comes up tails more than 10 times?
+130516 For (a), we have
C(12, 7) * (.389)^7 * (.611)^5 = about .09 or about 9/100
For (b), we have
C(12,10) * (.389)^10 * (.611)^2 = .00195
+ C(12,11) * (.389)^11) * (.611)^1 = .000226
+ C(12,12) * (.389)^12) * (.611)^0 = .000012
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about .0022 = about 22/10,000 = 11/5000
