Answer:
7 × 8
Step-by-step explanation:
7 number of students × 8 books each student has 7 × 8 = 56
Answer:
The interval [32.6 cm, 45.8 cm]
Step-by-step explanation:
According with the <em>68–95–99.7 rule for the Normal distribution:</em> If 
is the mean of the distribution and s the standard deviation, around 68% of the data must fall in the interval
![\large [\bar x - s, \bar x +s]](https://tex.z-dn.net/?f=%5Clarge%20%5B%5Cbar%20x%20-%20s%2C%20%5Cbar%20x%20%2Bs%5D)
around 95% of the data must fall in the interval
![\large [\bar x -2s, \bar x +2s]](https://tex.z-dn.net/?f=%5Clarge%20%5B%5Cbar%20x%20-2s%2C%20%5Cbar%20x%20%2B2s%5D)
around 99.7% of the data must fall in the interval
![\large [\bar x -3s, \bar x +3s]](https://tex.z-dn.net/?f=%5Clarge%20%5B%5Cbar%20x%20-3s%2C%20%5Cbar%20x%20%2B3s%5D)
So, the range of lengths that covers almost all the data (99.7%) is the interval
[39.2 - 3*2.2, 39.2 + 3*2.2] = [32.6, 45.8]
<em>This means that if we measure the upper arm length of a male over 20 years old in the United States, the probability that the length is between 32.6 cm and 45.8 cm is 99.7%</em>
Answer:
7 = 49 ÷ r
Step-by-step explanation:
To find the equation that is true when r = 7, we need to find a number after the equals sign that is a multiple of 7.
Multiples of 7:
7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77...
Therefore, the only answer option in which the number after the equals sign is a multiple of 7 is:
7 = 49 ÷ r
To prove this, input r = 7 into each of the equations:
6 = 30 ÷ r
⇒ 6 = 30 ÷ 7
⇒ 6 ≠ 4.285... ← incorrect!
7 = 54 ÷ r
⇒ 7 = 54 ÷ 7
⇒ 7 ≠ 7.714... ← incorrect!
7 = 49 ÷ r
⇒ 7 = 49 ÷ 7
⇒ 7 = 7 ← correct!
9 = 72 ÷ r
⇒ 9 = 72 ÷ 7
⇒ 9 ≠ 10.285... ← incorrect!
