College math problem, please help!

Question

A jar contains 4 red marbles numbered 1 to 4 and 6 blue marbles numbered 1 to 6. A marble is drawn at random from the jar. Find the probability of the given event. Enter exact value. Do not round.

(a) The marble is red

Your answer is :   

(b) The marble is odd-numbered

Your answer is :   

(c) The marble is red or odd-numbered

Your answer is :   

(d) The marble is blue and even-numbered

Your answer is :  

Answer 1

So first off, there are 10 marbles altogether, so it's always going to be a number out of 10. That will hopefully make things easier to understand for this problem.

(a) Okay, so for (a), since there are 4 red marbles, this will make the answer be 4/10 or also 2/5 or 40%.

(b) For this one, since there are 2 odd-numbered red marbles and 3 odd-numbered blue marbles, this will make this answer be 5/10 or also 1/2 or 50%.

(c) For this one, since there are 4 red marbles and 3 odd-numbered marbles of the remaining marbles, this will make this answer be 7/10 or 70%.

(d) For this one, since there are 3 blue odd-numbered marbles, this will make this answer be 3/10 or 30%.

Answer 2

If all the events occur independently and the marble is replaced after each occurrence, then

(a) P(marble red) = 4/10

(b) P(odd) = 5/10

(c) P(red or odd) = 4 red + 3/6 of the blue for 1,3, and 5 (the odd #'s) = 7/10

(d) P(blue and even) = so it has to be both blue AND even = of the 6 blue marbles, 3 are even (2, 4, and 6) so 3/10.