a birthday child reaches into a bag filled with toys ( 1 yo - yo , 1 ball , 1 whistle , and 1 box crayons ) . if the child randomly picks 3 toys , what is the probability the child will pick the yo - yo and a ball as two of the 3 toys ?
Choose the correct choice from the following:	A) 1 / 3	B) 1 / 2	C) 1 / 4	D) 1 / 5	E) 2 / 5

Rationale: combination formula : ncr = n ! / ( r ! ( n - r ) ! ) , where n is the population / set , and r is the sample / subset . total number possible = 4 c 3 - 4 ! / ( 3 ! ( 4 - 3 ) ! ) = 4 number yo - yo possible = 1 c 1 = 1 number ball possible = 1 c 1 = 1 number other possible = 2 c 1 = 2 probability formula : p ( a ) = ( number favorable outcomes ) / ( total number possible outcomes ) p ( yb ) = ( 1 c 1 ) ( 1 c 1 ) ( 2 c 1 ) / 4 c 3 = 2 / 4 = 1 / 2 answer : b
Answer: B