Statistics , finding the probability

a couple has 3 children, find the probability that exactly 2 boys or 2 girls

I don't know how to figure this one out.. how is the answer 6/8? i would think 2/8 cause only possibility is GG and BB

There are 8 possible sequences of genders of the 3 children, one of which
is all girls and another of which is all boys. The rest have either 2 boys
and 1 girl or 1 boy and 2 girls. So the probability will be 6/8 = 3/4.

Edit: Writing out the 8 possible sequences, we have

GGG, GGB, GBG, GBB, BBB, BBG, BGB, BGG.

The children are distinct, making more possibilities. Symbolically, you're dealing with an ordered triplet, rather than a multiset.

(G, G, G)
(G, G, B)
(G, B, G)
(G, B, B)
(B, B, B)
(B, B, G)
(B, G, B)
(B, G, G)

That's all 8 possibilities for the genders of the three children, youngest to oldest, 6 of which contain exactly two of the same gender.

3 children... then the probability of (2 boys or 2 girls) is 1....

What you might be looking for is P(2 boys) or P(2girls)
SO
A....B...C
B....B....B
B....B....G
B....G....B
G....B....B
B....G....G
G....B....G
G....G....B
G....G....G

are all the possibilities
So, 8 possibilities...
Of these, 3 have two boys, and 3 have 2 girls That's 6
So (P(2 boys) or P(2 girls)) = (3/8 + 3/8) = 6/8

Nope, think again..........
GGG
GGB
GBG
GBB
BBB
BBG
BGB
BGG

Out of these 8 possibilities, all but 2 have either 2 boys or 2 girls, leaving 6 that meet the test.

The probability of exactly 2 boys OR 2 girls is 6/8 = 3/4 = 75% = 0.75

The law of probability cannot be used in procreation unless one looks at both parents Family Tree/Ancestry.

The gender of the 3 existing children is a clue, but not an absolute.
.

THREE children

GGG
GGB
GBG
BGG
BBG
BGB
BBG
BBB

Only all boys or all girls does not meet the definition