Robert has an envelope containing 24 photographs. Six of the photographs are of Robert, and the rest are of his friend Katie. He will choose 4 photographs at random. If the first 3 are of Robert.

a. 1/2

b.3/4

c. 6/7

d. 9/10

Robert has an envelope containing 24 photographs. Six of the photographs are of Robert, and the rest are of his friend Katie. He will choose 4 photographs at random. If the first 3 are of Robert.

a. 1/2

b.3/4

c. 6/7

d. 9/10

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Vienna, VA

Like Phillip said,

# of Photos of Katie = PK = 18

# of Photos of Robert = PR = 6

Total # of photos = 18 +6 = 24

After getting 3 photographs of Robert (24 -3),

PK = 18

PR = 3

TOTAL # of Photos remaining = 18 + 3 = 21 photos

=(18=number of photos of Katie)/(21=number of remaining photos) = 6/7 the answer is C.

Olney, MD

Again, after removing 3 pictures of Robert, there are 21 photos remaining in the envelope, 3 of Robert and 18 of Katie. The probability that the next photo will be of Katie is:

P = (Number of Photos of Katie Remaining) / (Total Number of Photos Remaining)

Remember to reduce the fraction. Let me know what you get!

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