Answer:
Step-by-step explanation:
There are a total of 7 + 9 + 2 = 18 balls in the vase, therefore, when not replacing the first ball, there would be 18 · 17 = 306 ways to pull 2 balls. There are 2 ways to choose the first black ball and then 1 way to choose the second black ball so there are 2 · 1 = 2 ways to choose 2 black balls. Therefore, the probability is 2 / 306 = .
Answer:
40 mph.
Step-by-step explanation:
Suppose grandma's house is 30 miles away (any distance would do but 30 is convenient).
Speed = distance / time
time = distance / speed
Time to get there = 30/60 = 1/2 hour.
Time to get back = 30/30 = 1 hour
Average speed = total distance/ total time
= (30 + 30) / ( 1 + 1/2)
= 60 / 1.5
= 40 miles per hour.
You cannot take the average of the speeds directly
(60+ 30)/2 = 45 is not correct as you cannot average ratios ( speed is a ratio).
A proportion is an equation that states that two ratios are equal
Step-by-step explanation:
the easiest approach with a given point and the slope of the line is the point-slope form :
y - y1 = a(x - x1)
where "a" is the slope, and (x1, y1) is a point on the line.
so, we get
y - -8 = 4(x - -3)
y + 8 = 4(x + 3)
if we need the slope-intercept form
y = ax + b
we now simplify the point-slope form
y + 8 = 4x + 4×3 = 4x + 12
y = 4x + 4
