Rectangle A ~ Rectangle B
Answer:
66
Step-by-step explanation:
Use the formula for the mean of a set of numbers:
sum of the numbers
average = --------------------------------
count of numbers
Here we know that the average mark was 68, so we can write:
75 + 62 + 84 + 53 + x
average = 68 = ----------------------------------
5
or 274 + x
68 = -------------------
5
Solving for x, we multiply both sides by 5: 340 = 274 + x.
Subtracting 274 from both sides effectively isolates x:
340 = 274 + x
- 274 -274
------------------------
66 = x
The fifth student's mark was 66.
Answer: D
Step-by-step explanation:
9514 1404 393
Answer:
- (x +1)² = 4
- (D) x = -1 ±2
Step-by-step explanation:
Start by getting the x-terms on one side of the equal sign. We can do that by subtracting x from both sides.
3 = x² +2x
Now, add the square of half the x-coefficient.
3 +1 = x² +2x +1
(x +1)² = 4 . . . . . . . . write as a square in the desired form
__
To solve, take the square root, and add the opposite of the left-side constant.
x +1 = ±2
x = -1 ±2 . . . . . . matches choice (D)
