20% decrease should be the answer
Total cards = 52
Total red cards = 26
Total black cards = 26
P(one red and one black) = P(red and then black)+ P(black and then red)
P(one red and one black) =(26/52)(26/51) + (26/52)(26/51)
P(one red and one black) = 26/51 (Answer A)
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Answer: 26/51 (Answer A)
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Answer:
B. 0.4
Step-by-step explanation:
Use the definition of the probability
You have to find the probability that a randomly selected reference book is hard cover. Hence, from the table
- Number of all possible outcomes = Number of Reference books = 25
- Number of all favorable outcomes = Number of Hardcover Reference books = 10
So, the probability is
Let's solve this system of equations through substitution.
We have these two equations.
-7x-2y=14
6x+6y=18
Now let divide the second equation by 6.
6x+6y=18 ----> x+y=3
Next, let us move y to the right side of the equation.
x+y=3 -------> x=3-y (x equals 3-y)
Because we found out that what x is in terms of y, we can input that in for every instance of x in this equation below.
-7x-2y=14 becomes -7(3-y)-2y=14 (Why? Because x equals 3-y!)
We have a one variable equation now and can solve for y.
-7(3-y)-2y=14
-21+7y-2y=14
5y=35
y=7
Plug in 7 for y in any equation to find x.
x+y=3
x+7=3
x=-4
answer: x=-4, y=7
