There are 8 black chips and 6 white chips, 14 chips in total. In this situation the probability to pick a black chip is 8/14=4/7.
When one white chip was removed, then only 5 white chips left and the total number of chips became 13. In this situation the probability to pick a black chip is 8/14=4/7.
When second white chip was removed, then ther left 4 white chips and the total number of chips became 12. Now the probability to pick a black chip is 8/12=2/3 as needed.
Answer: Must be removed 2 white chips. Correct choice is B.
Answer:
38: is A
39: is A
Step-by-step explanation:
Answer:
The length is 7 m
The width is 10 m
Step-by-step explanation:
length = x
width = 2x - 4
length * width = area
It is given that the area is 70 
From there
x * (2x - 4) = 70
- 4x = 70
- 4x - 70 = 0
- 2x - 35 = 0
Now we have a quadratic equation, which is a + bx + c = 0, where a 
0
In this equation a = 1, b = -2 and c = -35
Discriminant (D) formula is b² - 4ac
D = 
- 4 * 1 * (-35) = 144 > 0
This discriminant is more than 0, so there are two possible x
Their formulas are 
and 
= 
= -5 < 0 (the length of the rectangle has to be more than 0, so we don't use this x)
= 
= 7 > 0 (this one is right)
Calculating the dimensions
length = x = 7 (m)
width = 2x - 4 = 2 * 7 - 4 = 10 (m)
Answer:
a = -8
Step-by-step explanation:
19 = -3a - 5
Add 5 to both sides.
24 = -3a
Divide both sides by -3.
-8 = a
Switch sides.
a = -8
