There is a spinner with 5 equal sections. Red, Red, Blue, Green and Yellow.

1.If Jo spins a Blue and a Red (or a Red and a Blue) he wins. What is the PROBABILITY that Jo wins?

2. If Mara spins a Red and a Red or a Yellow first then a Red she wins. What is the PROBABILITY that Mara wins?

Answer :

We know Probability P ( E ) =  Number of desired events n (E )Total number of events n ( S)

1 )  If Jo spins a Blue and a Red (or a Red and a Blue) he wins

SO, Desired events  { ( B , R  )  And ( R  , B ) }
Total events if Blue comes first  : {  ( B  , R ) , ( B  , G  )  , ( B  ,Y ) }

Total events if Red comes first  : { ( R , R ) , ( R , B  ) , ( R , G ) , ( R , Y ) }

SO, Winning probability of Jo if combination ( B , R ) came  = 13

Winning probability of Jo if combination ( R , B ) came  = 14

So, Winning probability of jo if a Blue and a Red  or a Red and a Blue comes  = 13  + 14  =  4 + 3 12  = 712  ( Ans  )

2 )  If Mara spins a Red and a Red or a Yellow first then a Red she wins.

SO, Desired events  { ( R , R  )  And ( Y  , R ) }
Total events if Yellow comes first  : {  ( Y  , R ) , ( Y  , G  )  , ( Y  ,B ) }

Total events if Red comes first  : { ( R , R ) , ( R , B  ) , ( R , G ) , ( R , Y ) }

SO, Winning probability of Jo if combination ( Y , R ) came  = 13

Winning probability of Jo if combination ( R , R ) came  = 14

So, Winning probability of  Mara , If she spins a Red and a Red or a Yellow first then a Red   = 13  + 14  =  4 + 3 12  = 712  ( Ans  )
 

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