Please, could you check my solution of this two problems?
1) The 30% of the products has a positive nominal value and the 70% of the products has a negative nominal value. To control the products are chosen 3 random of 100.
What is the probability that at least one product has a positive bias?
My solution:
[C(30,1)*C(70, 2)+C(30,2)*C(70,1) + C(30,3)*C(70,0)] / C(100,3) = 106960/1611700 = 0,66
Is it good?
2) A Bus is stopping on 10 bus stops. In the bus are 4 passengers. What is probability that no 2 passengers does not exit the bus at the same time?
My solution:
P = 10! / (10^4 * (10-4)!) = 0,504
Is it good?
Thank you very much for every answer! I'm sorry for my English... :-)