Question

There are four blue marbles, an unknown number of red (r) marbles, and six yellow marbles in a bag. Which expression represents the probability of randomly selecting a blue marble, replacing it, and then randomly selecting a red marble? StartFraction 4 over 10 EndFraction (StartFraction r over 10 EndFraction) StartFraction 4 over 10 r EndFraction (StartFraction 4 over 10 r EndFraction) StartFraction 4 over 10 + r EndFraction (StartFraction r over 10 + r EndFraction) StartFraction 4 over 10 r EndFraction (StartFraction r over 10 r EndFraction)

Answer 1

C. 4/10+r (r/10+r)

Explanation:

EDG20

Answer 2

4/ (10+r) * r/ (10+r)

Explanation:

four blue marbles, an unknown number of red (r) marbles, and six yellow marbles in a bag = 4+r+6 = 10+r marbles

P( blue) = blue marbles / total marbles

= 4/ (10+r)

Then replace

P( r) = red marbles / total marbles

= r/ (10+r)

P( blue replace ,red) =P ( blue ) * P(red)

= 4/ (10+r) * r/ (10+r)

= 4r / ( 10+r) ^2