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Reil [10]
2 years ago
15

Answer fast for pts

Mathematics
2 answers:
NeTakaya2 years ago
7 0
  • Maria arrived at 8:30
  • It's can't be told that no one have arrived before her
  • She registered the times between 8:30 to 9:30 .
  • She hasn't registered the data of students who came before her .
  • So it's not a representative sample
sdas [7]2 years ago
4 0

Answer:

Since she arrived at 8:30 its not accurate because her records started at the time she arrived so she didnt get the times of the students that arrived before her

Step-by-step explanation:

Hope this helps:))

You might be interested in
A riverboat travels 54 km downstream in 2 hours. It travels 57 km upstream in 3 hours. Find the speed of the boat and the speed
irakobra [83]

Here we must write and solve a system of equations to find the speed of the boat and the speed of the stream. We will find that the boat's speed is 23km/h and the river's speed is 4km/h.

First, remember the relation:

Distance = Speed*Time.

Now let's define the variables we will be using:

  • B = boat's speed
  • R = river's speed.

When the boat travels downstream, the total speed of the boat is the speed of the boat plus the speed of the river, and we know that in that case it travels 54km in 2 hours, then:

54km = (B + R)*2h

When the boat travels upstream, we must subtract the speed of the river. In that case, we know that the boat travels 57km in 3 hours, then we have:

57km = (B - R)*3h

Then our system of equations is:

54km = (B + R)*2h

57km = (B - R)*3h

To solve this, first, we need to isolate one of the variables in one of the equations, let's isolate B in the second one:

57km = (B - R)*3h

57km/3h + R = B

19 km/h + R = B

Now we can replace that in the other equation:

54km = (B + R)*2h

54km/2h = B + R

27 km/h = B + R = (19 km/h + R) + R

Now we can solve this for R:

27 km/h = 19km/h + 2*R

27 km/h - 19km/h = 2*R

8 km/h = 2*R

(8km/h)/2 = 4km/h = R

Now that we know the value of R, we can use:

B = 19 km/h + R  = 19 km/h + 4km/h = 23 km/h

So the boat's speed is 23km/h and the river's speed is 4km/h.

If you want to learn more, you can read:

brainly.com/question/12895249

5 0
2 years ago
What is 11x(-6)?<br> please answer i really need this!
navik [9.2K]

Answer:

-66

Step-by-step explanation:

11 × (-6) = -66

8 0
3 years ago
Read 2 more answers
8×(30+2)=(8×_)+(8×2)
irinina [24]
Using the distributive property, a(b+ c) = ab + ac. In this case, b is 30, so the blank is 30.
6 0
3 years ago
Read 2 more answers
What must be added to 70 so it will divide exactly into five groups of 16
natulia [17]

Answer:

10

Step-by-step explanation:

x+70=16(5)\\\\x+70=80\\\\x=10

Therefore, the number is 10

5 0
2 years ago
a cyclist rides her bike at a speed of 2 meters per second. what is the speed in kilometers per hour? how many kilometers will t
zaharov [31]

1) 2m/s = 2*18/5 =7.2Km/h

2)In 3 hour, he would travel, 7.2*3 = 21.6Km.

7 0
2 years ago
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