Answer:
DB = 6
Step-by-step explanation:
See the attached figure to the question.
Since O is the center of the given circle, so AB and CD are diameters of the circle.
Hence, AO = CO = OD = OB = radius of the circle = 6
In Δ OAC, we have AO = OC. Hence, ∠ A = ∠C = 60° {Given that ∠OAC = 60°}
So, ∠ AOC will automatically become 60°. {As the sum of all the angles of a triangle is 180°}
So, Δ AOC is equilateral triangle.
Now, ∠ AOC = ∠ BOD = 60° {Since, they are vertically opposite angles}
Now, in Δ BOD, we have DO = OB. Hence, ∠ D = ∠ B = 60° {As the sum of all the angles of a triangle is 180°}
So, Δ BOD is also an equilateral triangle.
So, DB = BO = DO = 6. (Answer)
Answer:
Afternoon class has more students.
Step-by-step explanation:
Let m be the number of students in the morning class and n be the number of students in the afternoon class.
The average score for the students in the morning class was 80, then the sum of their scores is 
The average score for the students in the afternoon class was 86, then the sum of their scores is 
The sum of the scores of both classes is

and the average score is

The average (arithmetic mean) score for the two classes combined was 84, then

This means n is greater, so afternoon class has more students.
Answer:
3/20 of the cover page is text about endangered species.
Step-by-step explanation:
We know that 3/8th of the page is text, and 2/5ths of that text is about endangered species.
So all we have to do is find out how much 2/5ths of 3/8ths are, which can be done simply via fraction multiplication.
3/8 * 2/5 = ?
For multiplying fractions, we multiply the top parts together, and then the bottom parts together. So 3/ 8 * 2/5 would be equal to (3*2) / (8*5). This gives us 6 / 40 which can be simplified to 3/20.
So 3/20ths of the cover page is about endangered animals.
The speed is the ratio between the distance and the time:

Data:
d=6343miles
t=9h

Then, the plane traveled at a speed of 704.77 miles per hour.
Answer:
1. B
2. A
3. C
Step-by-step explanation: