Answer:
3.4
Step-by-step explanation:
Standard deviation of a population is defined as:
σ² = ∑(xᵢ − μ)² / n
The standard deviation of a sample is defined as:
s² = ∑(xᵢ − x)² / (n - 1)
It's not clear which one we have, so let's calculate both.
First, we must find the mean.
μ = (5+12+15+10+12+6+8+8) / 8
μ = 9.5
Now we find the squares of the differences:
(5-9.5)² + (12-9.5)² + (15-9.5)² + (10-9.5)² + (12-9.5)² + (6-9.5)² + (8-9.5)² + (8-9.5)²
= 80
Divide by n:
σ² = 80 / 8
σ² = 10
And take the square root:
σ = √10
σ ≈ 3.2
That's not one of the answers, so let's try the standard deviation of a sample instead of a population.
Instead of dividing by n, we'll divide by n-1:
s² = 80 / 7
And take the square root:
s = √(80/7)
s ≈ 3.4
So that must be it.
Answer:
15.6 ft
Step-by-step explanation:
Let's call
- a: distance from the top of the ladder to the ground = 10 ft
- b: distance from the bottom of the ladder to the bottom of the slide = 12 ft
From Pythagorean theorem:
c² = a² + b²
c = √(10² + 12²)
c = 15.6 ft
Answer:
A. 57.2
Step-by-step explanation:
Given: Nelly runs = 10-mile race in 88 minutes. At the same rate but 6.5-mile race
To find: How long it would take him to run a 6.5-mile race
Solution: To calculate the how long;
<u>How to calculate running pace</u>
- Divide your run time by your distance
- If you ran 3 miles in 30 minutes: 30 min ÷ 3 mi = 10 minutes per mile pace
<u>How to calculate run distance</u>
- Divide your running time by your pace
- If your pace is 8 minutes per mile and you ran for 32 minutes: 32 min ÷ 8 min per mi = 4 miles
<u>How to calculate run time</u>
- Multiply your pace by your distance
- If your pace is 9.5 minutes per mile and you ran 3 miles: 9.5 min per mi × 3 mi = 28.5 minutes = 28 minutes, 30 seconds
<u>How to calculate running speed</u>
- Divide your run distance by your run time
- If you ran 2.5 miles and you ran for 20 minutes:
2.5 mi ÷ 20 min = 0.125 miles per minute