Answer:
uhmm...
Step-by-step explanation:
4/10 multiplied to 2/3 is 4/15.
The final probability is the weighted average of the playing probabilities calculated over the possible weather options:
P(john practices cello; given that it rains) * P(it rains) +
P(john practices cello; given that it does not rain) * P(it does not rain) =
0.6 * 0.7 + 0.4 * 0.3 = 0.54
The probability is 54%