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Alecsey [184]
3 years ago
13

A group of students calculated their average score at a spelling bee. They realized that if one of them scored 9 more points, th

eir average score would be 81 points. If one of them scored 3 points less, their average score would be 78 points. How many students were in the group?
Mathematics
1 answer:
alukav5142 [94]3 years ago
8 0

Answer: There are 4 students in the group.

Step-by-step explanation:

Let the number of students in the group be n

If one of them scored 9 more points , their average score would be 81 points.

So, our equation (1) will be

\frac{\sum x+9}{n}=81\\\\\sum x+9=81n

Similarly,

If one of them scored 3 points less, their average score would be 78 points.

So, our equation (2) will be

\frac{\sum x-3}{n}=78\\\\\sum x-3=78n

So, from equation (1) and (2) we get:

81n-9=\sum x=78n+3\\\\81n-9=78n+3\\\\81n-78n=3+9\\\\3n=12\\\\n=\frac{12}{3}\\\\n=4

Hence, there are 4 students in the group.

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A fair spinner has 9 equal sections: 4 red, 3 blue and 2 green.
Gennadij [26K]

Answer:

14/81

Step-by-step explanation:

The probability of getting a green is number of green sections ÷ total number of sections = 2/4+3+2 = 2/9

Probability of not getting a green is = 1 - probability of getting a green = 1 - 2/9 = 7/9

Now we calculate the probability of not getting 2 consecutive greens. I.e probability of getting a green the first time and not getting it the second time= (2/9 × 7/9) = 14/81

6 0
3 years ago
Разстоянието между селищата A и B е 410 км.От A за B пътува лека кола със скорост 90km/h, а 1 h по-късно от B за A тръгва камион
harkovskaia [24]

4,56 км / ч просто разделят ускорението и точката на среща.

4 0
3 years ago
A cyclist cycles a distance of 40 miles in a time of 2 hours. what is her average speed?
snow_lady [41]

Answer:

see this and it by your own

Step-by-step explanation:

How do you find average speed with distance and time?

Divide the distance by the time.

This will give you the average speed per unit of time, usually hour. So, if Ben traveled 150 miles in 3 hours, his average speed is 50 miles per hour

How do you find average speed with hours and minutes?

How to calculate average speed. Speed is distance divided by time. Simply put, if you drove 60 kilometer's for one hour, it would look like this: Speed = distance (60 km) / time (1 hour) = 60km/h.

6 0
3 years ago
Use Newton's method with initial approximation x1 = −2 to find x2, the second approximation to the root of the equation x3 + x +
nevsk [136]

Answer:

x_2 \approx -1.769

Step-by-step explanation:

Let f(x)=x^3+x+7

So f'(x)=3x^2+1

x_{n+1}=x_n-\frac{f(x_n)}{f'(x_n)}

Let x_1=-2

We are going to find x_2

So we are evaluating -2-\frac{f(-2)}{f'(-2)}

First step find f(-2)

Second step find f'(-2)

Third step plug in those values and apply PEMDAS!

f(-2)=(-2)^3+(-2)+7=-8-2+7=-10+7=-3

f'(-2)=3(-2)^2+1=3(4)+1=12+1=13

So

x_2=-2-\frac{-3}{13} \\\\ x_2=\frac{-26+3}{13} \\\\ x_2=\frac{-23}{13} \\\\ x_2 \approx -1.769

5 0
3 years ago
----------- are used to represent an unknown quantity in a mathematical expression.
anastassius [24]
A letter or symbol is used to represent an unknown quantity
4 0
3 years ago
Read 2 more answers
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