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3 years ago

8

A bag contains 10 marbles: 2 are green, 4 are red, and 4 are blue. Tammy chooses a marble at random, and without putting it back

, chooses another one at random. What is the probability that both marbles she chooses are blue?

1 answer:

erastovalidia [21]3 years ago

8 0

There are 10 marbles, out of these 10 there are 4.

The probability of her picking a blue marble is 4/10

This can be simplified to 2/5

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A researcher claims that the variation in the salaries of elementary school teachers is greater than the variation in the salari

guajiro [1.7K]

Answer:

a

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

b

$F_{critical} = 1.8608$

c

$F = 2.9085$

d

The decision rule is

Reject the null hypothesis

e

There is sufficient evidence to support the researchers claim

Step-by-step explanation:

From the question we are told that

The first sample size is $n_1 = 30$

The sample variance for elementary school is $s^2_1 = 8324$

The second sample size is $n_2 = 30$

The sample variance for the secondary school is $s^2_2 = 2862$

The significance level is $\alpha = 0.05$

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

Generally from the F statistics table the critical value of $\alpha = 0.05$ at first and second degree of freedom $df_1 = n_1 - 1 = 30 - 1 = 29$ and $df_2 = n_2 - 1 = 30 - 1 = 29$ is

$F_{critical} = 1.8608$

Generally the test statistics is mathematically represented as

$F = \frac{s_1^2 }{s_2^2}$

=> $F = \frac{8324 }{2862}$

=> $F = 2.9085$

Generally from the value obtained we see that $F > F_{critical }$ Hence

The decision rule is

Reject the null hypothesis

The conclusion is

There is sufficient evidence to support the researchers claim

4 0

3 years ago

Shaun has five coins in his pocket. If he empties the coins onto a table, what is the probability that all five coins will land

Anastasy [175]

Answer:

A. 1/32

Step-by-step explanation:

Ok, the probability for one of the coins to land on heads is 1/2 cause a coin have to sides and chance is 50% that it will land on either of its sides.

If you have 2 coins the probability will be 1/2 for the first coin to land on heads and 1/2 for the second one. The overall probability for 2 coins would be (1/2)*(1/2)=1/4. You could also see it is 1/4 because all of the possible combinations of 2 coins are 4 (HH, HT, TH, TT) and HH is one of four.

It's the same if you have 5 coins. The probability will be (1/2)*(1/2)*(1/2)*(1/2)*(1/2)=1/32 in other words HHHHH is one of 32 possible combinations of 5 coins.

5 0

3 years ago

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goldfiish [28.3K]

Answer:

Step-by-step explanation:

The answer is C

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3 years ago

If ANQZ - ACBK, find BK. *<br><br>O BK = 39<br>O BK = 16<br>O BK = 65<br>O BK = 27<br>

patriot [66]

9514 1404 393

Answer:

(c) BK = 65

Step-by-step explanation:

Corresponding sides are proportional in similar triangles, so ...

ZT/ZQ = KF/KB

27/(2x +7) = 45/(4x+1)

27(4x+1) = 45(2x +7) . . . cross-multiply

3(4x +1) = 5(2x +7) . . . . divide by 9

12x +3 = 10x +35 . . . . . eliminate parentheses

2x = 32 . . . . . . . . . . . . . subtract 10x+3

x = 16 . . . . . divide by 2

Then the length of BK is ...

BK = 4x+1 = 4·16 +1

BK = 65

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3 years ago

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arlik [135]

Answer:

x=2

Step-by-step explanation:

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3 years ago