Complementary events must have a sum of 1.

This is a true statement.

Consider two events A and B. We say they are complementary if P(A)+P(B) = 1

This means that either event A or event B must happen, since the "1" represents 100% probability. Having a probability of 100% means absolute certainty.

Example:

A = the event it rains

B = the event it does not rain

P(A) = 0.30 = 30% chance of rain

P(B) = 0.70 = 70% chance it does not rain

P(A)+P(B) = 0.30+0.70 = 1

So this shows the two events are complementary.

3< x< 5

step-by-step explanation:

|x - 4| < 1

there are two solutions, one positive and one negative.   remember to flip the inequality when taking the negative solution

x-4 < 1       x-4 > -1

add 4 to each side

x-4+4 < 1+4       x-4+4 > -1+4

x< 5                 x> 3

3< x< 5

to plot points   for x just start at the origin (middle) and go to the left however many times it say(if the number is a positive) if the number is a negative then go right however many times it says if it is 0 go nowhere

now keep you pencil there and go up however many times it says on y(if it is positive) if it is negative then go down however many times it says. if it says 0 go nowhere.

you have just plotted a point! now when you finish plotting all of them connect them with a ruler

plot each point as (-3, 7), (0,4), (3,1), (8,-4)   in the parenthesis on the left of the comma is x and the right is y.