Answer:
Not probabillity of picking a green marble is 80%
Step-by-step explanation:
The Z-score is calculated by the formula below

Step 2: Substitute the given parameters in the formula

Hence, the z-score of a person who scored 145 on the exam is -0.5
S= number of small boxes
l= number of large boxes
equation 1: s+l=120
equation 2: 15s+45l=3300
solve by elimination, multiply equation 1 by -15.
-15(s+l=120) = -15s-15l=-1800 add to equation 2.
-15s+15s-15l+45l=-1800+3300 = 30l=1500
30l=1500 , l=50
s+l=120, s+50=120 --> s=70
Ricky works almost 7 hours if your rounding.