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3 years ago

11

Katherine has 4 red pens, 6 blue pens, and 11 black pens in her book bag. If she randomly pulls out one pen, what is the probabi

lity that it will be black?

1 answer:

sashaice [31]3 years ago

6 0

Answer: 52.38%

Step-by-step explanation:

11 out of 21

11/21

.5238

52.38%

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Find a counterexample: Two sides of a

Shkiper50 [21]

Answer: Any isosceles triangle is a counter example. More specifically, a triangle with sides 7, 7 and 3

When forming your triangle, make sure you apply the triangle inequality theorem. This is the idea where adding any two sides leads to a result larger than the third side. So we have

7+7 = 14 which is larger than 3

7+3 = 10 which is larger than 7

By definition, an isosceles triangle has two congruent sides. Some books say "at least 2 congruent sides", but I'll go with the first definition. If you want all three sides to be congruent, then you'd go for the term "equilateral".

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3 years ago

What multiplication fact could you use to find a number that can be divided evenly by 8 and by 9

Ad libitum [116K]

72 would be a good one

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3 years ago

Read 2 more answers

Somebody please help me

miss Akunina [59]

I chose x^3, it would be a cubic function , then it’s -(x-6 )^3 -2

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3 years ago

Write the series using summation notation.<br><br> 4 + 8 + 12 + 16 + 20+ . . . + 80

zhannawk [14.2K]

Answer:

$\sum ^{20} _{n \to \11} 4n$

Step-by-step explanation:

In order to write the series using the summation notation, first we need to find the nth term of the sequence formed. The sequence generated by the series is an arithmetic sequence as shown;

4, 8, 12, 16, 20...80

The nth term of an arithmetic sequence is expressed as Tn = a +(n-1)d

a is the first term = 4

d is the common difference = 21-8 = 8-4 = 4

n is the number of terms

On substituting, Tn = 4+(n-1)4

Tn = 4+4n-4

Tn = 4n

The nth term of the series is 4n.

Since the last term is 80, L = 4n

80 = 4n

n = 80/4

n = 20

This shows that the total number of terms in the sequence is 20

According to the series given 4 + 8 + 12 + 16 + 20+ . . . + 80 , we are to take the sum of the first 20terms of the sequence. Using summation notation;

4 + 8 + 12 + 16 + 20+ . . . + 80 = $\sum ^{20} _{n \to \11} 4n$

4 0

3 years ago

How to solve this question

VMariaS [17]

<span>The variance method is as follows.

-Sum the squares of the values in data set, and then divide by the number of values in data set
- From that, subtract the square of the mean (add all values and divide by number of values in the data set)

Our variance is

<span> $\displaystyle\sigma^2 = \frac{2^2 + 5^2 + m^2}{3} - \left(\frac{2 + 5 + m}{3}\right)^2$

Since variance has to be 14, we set $\sigma^2 = 14$ and solve for m

$14= \frac{4 + 25 + m^2}{3} - \left(\frac{7 + m}{3}\right)^2\ \Rightarrow \\ \\
14 = \frac{29}{3} + \frac{1}{3}m^2 - \frac{1}{9}(7+m)^2 \\ \\
14 = \frac{29}{3}+ \frac{1}{3}m^2 - \frac{1}{9}(49 + 14m + m^2) \\ \\
14 = \frac{29}{3}+ \frac{1}{3}m^2 - \frac{49}{9}- \frac{14}{9}m- \frac{1}{9}m^2 \\ \\
0 = \frac{-88}{9} -\frac{14}{9}m + \frac{2}{9}m^2
$

quadratic formula

$m = \displaystyle\frac{-b \pm \sqrt{b^2 -4ac}}{2a} \\
m = \frac{-(-\frac{14}{9}) \pm \sqrt{\left(-\frac{14}{9}\right)^2 - 4(2/9)(-88/9)} }{2(2/9)} \\
m = \frac{\frac{14}{9} \pm \sqrt{ \frac{196}{81} + \frac{704}{81} } }{\frac{4}{9} } \\
m = \frac{\frac{14}{9} \pm \sqrt{ \frac{900}{81} } }{\frac{4}{9} } \\
m = \frac{\frac{14}{9} \pm \sqrt{ \frac{100}{9} } }{\frac{4}{9} } \\
m = \frac{\frac{14}{9} \pm \frac{10}{3} }{\frac{4}{9} } \\
m = 11, -4$

-4 doesnt' work as it is not a positive integer

m = 11

</span></span>

5 0

3 years ago