a*****g
发帖数: 1320 | 1 1.How many of the letters in MATHCOUNTS have a horizontal line of symmetry?
2.Billy takes two marbles, without replacement, from a bag that contains
only six yellow marbles and three blue marbles. What is the probability that
he gets one marble of each color? Express your answer as a common fraction. | k***y
发帖数: 28 | 2 The following are just my guess:
1. Letter H,C,O has horizon symmetry
2. 4/9 | m***s
发帖数: 35 | 3 1yellow 1 blue
6/9 * 3/8
1blue +1 yellow
3/9 + 2/8
1/4 + 1/4= 1/2
Or another way:
Total possibility C(2, 9)= 36
combination of 2 yellow C(2,3) =3
combination of 2 blue C(2,6)= 15
Other possibility = (36-3-15)/36 =1/2 | t***h
发帖数: 5601 | 4 正解
【在 m***s 的大作中提到】
: 1yellow 1 blue
: 6/9 * 3/8
: 1blue +1 yellow
: 3/9 + 2/8
: 1/4 + 1/4= 1/2
: Or another way:
: Total possibility C(2, 9)= 36
: combination of 2 yellow C(2,3) =3
: combination of 2 blue C(2,6)= 15
: Other possibility = (36-3-15)/36 =1/2
|
|
