Seven ping-pong balls numbered 1-7 are put in a hat. Three balls are chosen without replacement. What is the probability that all three numbers are even numbers?
probability of 1st number being even : 3/7
probability of 2nd number being even : 2/6
probability of 3rd number being even : 1/5
probability of all 3 numbers being even : 3/7 2/6 1/5 = 6/210 = 1/35
The probability that all three numbers are even numbers is:
\(\dfrac{1}{35}\)
There are seven balls numbered as: 1-7
and the number of even numbers are: 3 ( i.e. 2,4 and 6 )
Three balls are chosen without replacement.
Hence, the probability that all three numbers are even numbers is given by:
Ratio of number of favorable outcomes to the total number of outcomes.
Hence, the probability is:
\(P(All\ three\ even\ numbers)=\dfrac{3_C_3}{7_C_3}\)
where the numerator represents that the balls drawn have even numbers.
and the denominator denote the choosing of 3 balls out of a total of 7 balls.
Hence, the probability is:
\(P(All\ three\ even\ numbers)=\dfrac{1}{35}\)