(1) 1/4 of the members are at least 35 years of age. But we don't how many members there are in club X. Not sufficient.
(2) members of the club X is 64/0.4 = 160.
(1)+(2) Sufficient.
0.3 + (0.7)(0.3) + (0.7)(0.7)(0.3)=0.657.
另一种:the opposite of the desired event is "leo doesn't hear a song he likes". that probability is (0.7)(0.7)(0.7) = 0.7^3, or 0.343.
therefore, the desired probability is 1 - 0.343, or 0.657.
Because geophysicists know that seismic waves become sluggish in hot, low-density rock, and speed up in colder, denser regions, they can now infer the temperatures and den- sities in a given segment of the interior.
外角等于另侧内角和,BAO等于20。