There are two ways to solve this problem.


One way is to use the formula  P = .      (1)

The denominator of this formula,  ,  is the number of combinations of 10 items taken 3 at a time.

In other words, it is the number of all triples that can be formed from 10 pieces of fruits.

The numerator,  ,  is the number of all triples of pears that can be formed of 6 pears.


 =  = 120.

 =  = 20.


Therefore, the probability under the question is  P =  = .



Another way is to write


    P =  = simplifying =  =  = ,    (2)


which leads to the same answer.


In formula (2),  first factor    is the probability to get one pear from 10 fruits; 

the factor    is the probability to get second pear from the remaining 9 fruits; 

and the last factor    is the probability to get third pear from the remaining 8 fruits;.