Answer:
A. 64/125
B. 124/125.
Step-by-step explanation:
A). As the events ( germinate or not germinate) are independent we multiply the probabilities.
Prob(All seeds germinate) = 4/5*4/5*4/5 = 64/125.
B). Probability of at least one germinating = 1 - probability that none germinate
Probability of 1 seed not germinating = 1 -45 = 1/5.
So Prob(at least one germinating)
= 1 - (1/5 * 1/5 * 1/5)
= 1 - 1/125
= 124/125.
He could have wrote -2.5 or -3.
To answer this question you should begin with the coin that has a higher value. If you start with the dime and then just add the correct number of pennies to total $0.40, you will see that you will need 3 dimes ($0.30) and 10 pennies ($0.10).
I used a guess and check strategy starting with 2 dimes.