Q. Sepasang suami istri merencanakan untuk mempunyai 4 orang anak. Jika variabel acak X menyatakan banyak perempuan, nilai dari P(X≤2) adalah .....
Define random variable and distribution: Define the random variable and the distribution.The random variable X represents the number of daughters in a family of four children. Assuming that the probability of having a daughter is the same as having a son, and each birth is independent of the others, X follows a binomial distribution with parameters n=4 (number of trials) and p=0.5 (probability of success, i.e., having a daughter).
Calculate probabilities of daughters: Calculate the probability of having 0, 1, or 2 daughters.We need to calculate P(X=0), P(X=1), and P(X=2) and then sum these probabilities to find P(X≤2).The probability mass function (PMF) for a binomial distribution is given by:P(X=k)=(kn)⋅pk⋅(1−p)n−kwhere “n choose k” is the binomial coefficient calculated as k!⋅(n−k)!n!.
Calculate P(X=0): Calculate P(X=0). Using the PMF: P(X=0)=(04)×(0.5)0×(0.5)4−0P(X=0)=1×1×(0.5)4P(X=0)=0.0625
Calculate P(X=1): Calculate P(X=1). Using the PMF: P(X=1)=(14)×(0.5)1×(0.5)4−1P(X=1)=4×0.5×(0.5)3P(X=1)=4×0.5×0.125P(X=1)=0.25
Calculate P(X=2): Calculate P(X=2).Using the PMF:P(X=2)=(24)×(0.5)2×(0.5)4−2P(X=2)=6×0.25×0.25P(X=2)=6×0.0625P(X=2)=0.375
Sum probabilities for P(X≤2): Sum the probabilities to find P(X≤2). P(X≤2)=P(X=0)+P(X=1)+P(X=2) P(X≤2)=0.0625+0.25+0.375 P(X≤2)=0.6875