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8_murik_8 [283]
3 years ago
11

Andromeda is an example of a/n _______ galaxy.

Chemistry
2 answers:
stellarik [79]3 years ago
6 0
<span>spiral galaxy. A spiral galaxy is characterized by a massive concentration of stars, dust, and gas that take the shape of a rotating disk. They are named this way because their fringes take a spiral formation that gradually connects to a dense cluster of stars at the center.</span>
Morgarella [4.7K]3 years ago
3 0
The answer is spiral
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What is the entropy of this collection of training examples with respect to the positive class B. What are the information gains
Alenkinab [10]

The data set is missing in the question. The data set is given in the attachment.

Solution :

a). In the table, there are four positive examples and give number of negative examples.

Therefore,

$P(+) = \frac{4}{9}$   and

$P(-) = \frac{5}{9}$

The entropy of the training examples is given by :

$ -\frac{4}{9}\log_2\left(\frac{4}{9}\right)-\frac{5}{9}\log_2\left(\frac{5}{9}\right)$

= 0.9911

b). For the attribute all the associating increments and the probability are :

  $a_1$   +   -

  T   3    1

  F    1    4

Th entropy for   $a_1$  is given by :

$\frac{4}{9}[ -\frac{3}{4}\log\left(\frac{3}{4}\right)-\frac{1}{4}\log\left(\frac{1}{4}\right)]+\frac{5}{9}[ -\frac{1}{5}\log\left(\frac{1}{5}\right)-\frac{4}{5}\log\left(\frac{4}{5}\right)]$

= 0.7616

Therefore, the information gain for $a_1$  is

  0.9911 - 0.7616 = 0.2294

Similarly for the attribute $a_2$  the associating counts and the probabilities are :

  $a_2$  +   -

  T   2    3

  F   2    2

Th entropy for   $a_2$ is given by :

$\frac{5}{9}[ -\frac{2}{5}\log\left(\frac{2}{5}\right)-\frac{3}{5}\log\left(\frac{3}{5}\right)]+\frac{4}{9}[ -\frac{2}{4}\log\left(\frac{2}{4}\right)-\frac{2}{4}\log\left(\frac{2}{4}\right)]$

= 0.9839

Therefore, the information gain for $a_2$ is

  0.9911 - 0.9839 = 0.0072

$a_3$     Class label      split point       entropy        Info gain

1.0         +                        2.0            0.8484        0.1427

3.0        -                         3.5            0.9885        0.0026

4.0        +                        4.5            0.9183         0.0728

5.0        -

5.0        -                        5.5            0.9839        0.0072

6.0        +                       6.5             0.9728       0.0183

7.0        +

7.0        -                        7.5             0.8889       0.1022

The best split for $a_3$  observed at split point which is equal to 2.

c). From the table mention in part (b) of the information gain, we can say that $a_1$ produces the best split.

4 0
3 years ago
How many significant figures does the following number contain: 385.01
dusya [7]

Answer:

5 significant figures

Explanation:

  • Zeros that come before any non-zero digits are never significant.

  • Zeros that are in between any non-zero digits are always significant.

  • Zeros that come after any non-zero digit are ONLY significant if a decimal point in present somewhere in the number. (In this case there is a decimal point, but there aren't any zeros at the end of this number.)

I have underlined the significant figures in this number:

<u>3</u> <u>8</u> <u>5</u> . <u>0</u> <u>1</u>

3 0
4 years ago
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