Answer:i think its the second choice sorry if im wrong
Step-by-step explanation:
Answer:
It is the third option: (10C1) (20C1( / 50C2.
Step-by-step explanation:
The number of ways of selecting 2 marbles = the number of combination of any 2 marbles in the 50 marbles in the bag and this is 50C2. It is combinations because the order of drawing the marbles does not matter.
The number of combinations of one being red and the other blue = 10C1 times 20C1.
So the answer is (10C1) (20C1( / 50C2.
28 men are needed to paint the room in 3 hours
<h3><u>Solution:</u></h3>
Given that it takes 12 hours for 7 men to paint a room
We are asked to find number of men required to paint the room in 3 hours
Recognize, "paint the room" is 1 task. One job.
7 men -------- 12 hours ------ 1 job
(7/7) = 1 men ------- 12 x 7 (84) ------- same 1 job
The one men is rate is 84 hours to do the job
We can express this as 1/84 jobs per hour, the one-person rate
Now lets find how many men needed to paint the room in 3 hours
Let the required number of men for 3 hours be "a"
The rates of each person is simply additive.

corresponds to rate x hours = jobs and "a" is a variable for how many men

Thus 28 men are needed to paint the room in 3 hours