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Given: R+B=8
Find R

1) R(R-1)/8*7= 5/14
R^2-R-20=0
(R-5)(R+4)
R=5 (or R=-4, it’s negative sorejected)
SUFFICIENT

2) RB/8*7=15/56
RB=15 &R+B=8
R^2-8R+15=0
(R-5)(R-3)
R=5 or R=3
INSUFFICIENT

ANSWER: A
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Let the number of red balls be r, and the number of blue balls be 8−r.

Statement 1.

The probability of selecting two red balls without replacement is given by: P(both red) = r/8 * (r-1)/7 = 5/14

Solving this will give r = 5 and r = -4, as negative value is not possible, r = 5 SUFFICIENT

Statement 2.

P(first red, second blue) = r/8 * (8-r)/7 = 15/56

Solving this gives r = 3 or r = 5 INSUFFICIENT

Answer A.
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