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kotegsom [21]
3 years ago
5

A band leader randomly selects 2 students out of 80 band members. If you and your brother are both band members, what is the pro

bability that you are both selected?
Mathematics
1 answer:
drek231 [11]3 years ago
6 0
The first time the band leader selects one member, the probability that either you or your brother gets selected would be 2 out of 80 or in fraction 2/80. Now, once one of you gets chosen, for the next selection, there are only 79 members left and the probability that the remaining one (between you and your brother) gets selected after is 1/79. So, if you are both to be selected, the combined probability for that to happen will be (2/80)(1/79) = 1/3160. Therefore, the answer is 1/3160<span>.</span>
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What fraction is greater than 0.7 and less than 0.8
posledela
0.7=7/10
0.8=8/10
0.75=3/4 this is between 0.7 and 0.8
6 0
3 years ago
Farmers know that driving heavy equipment on wet soil compresses the soil and injures future crops. Here are data on the "penetr
Greeley [361]

Answer:

Step-by-step explanation:

Hello!

To see if driving heavy equipment on wet soil compresses it causing harm to future crops, the penetrability of two types of soil were measured:

Sample 1: Compressed soil

X₁: penetrability of a plot with compressed soil.

n₁= 20 plots

X[bar]₁= 2.90

S₁= 0.14

Sample 2: Intermediate soil

X₂: penetrability of a plot with intermediate soil.

n₂= 20 (with outlier) n₂= 19 plots (without outlier)

X[bar]₂= 3.34 (with outlier) X[bar]₂= 2.29 (without outlier)

S₂= 0.32 (with outlier) S₂= 0.24 (without outlier)

Outlier: 4.26

Assuming all conditions are met and ignoring the outlier in the second sample, you have to construct a 99% CI for the difference between the average penetration in the compressed soil and the intermediate soil. To do so, you have to use a t-statistic for two independent samples:

Parámeter of interest: μ₁-μ₂

Interval:

[(X[bar]₁-X[bar]₂)±t_{n_1+n_2-2;1-\alpha/2}*Sa\sqrt{\frac{1}{n_1} +\frac{1}{n_2} }]

t_{n_1+n_2-2;1-\alpha/2}= t_{20+19-2;1-(0.01/2)}= t_{37; 0.995}= 2.715

Sa= \sqrt{\frac{(n_1-1)S_1^2+(n_2-1)S_2^2}{n_1+n_2-2} } = \sqrt{\frac{19*0.0196+18*0.0576}{20+19-2} }= 0.195= 0.20

[(2.90-2.29)±2.715*0.20\sqrt{\frac{1}{20} +\frac{1}{19} }]

[0.436; 0.784]

I hope this helps!

5 0
3 years ago
Find the products (3a-2)^2
Irina18 [472]

Hi there ! \(๑╹◡╹๑)ノ♬

Answer: \blue{ \boxed{ \bf  {9a}^{2}  - 12a + 4 } }

Step-by-step explanation:

\bf (3a - 2)^{2}  =

\bf (3a - 2) \times (3a - 2) =

\bf 3a \times 3a - 3a \times 2 - 2 \times 3a - 2 \times ( - 2) =

\bf  {9a}^{2}  - 6a - 6a + 4 =

\red{ \boxed{ \bf  {9a}^{2}  - 12a + 4 } }

8 0
2 years ago
4g + 7e + 4 + 9 + (-4e) + 11 = 5g + 3e + 15<br> This is an example of:
kiruha [24]

Answer:

An equation

Step-by-step explanation:

this can be solved too

4g + 7e + 4 + 9 + (-4e) + 11 = 5g + 3e + 15

combine like terms

4g + 3e + 24 = 5g + 3e + 15

3e + 24 = g + 3e + 15

24 = g + 15

9 = g

and

0 = e or *no solution* since e cancels itself out.

7 0
3 years ago
Which are not changed after a rotation? check all that apply.
vovikov84 [41]

Answer:

Size, angle measures, position of center of rotation, shape.

4 0
2 years ago
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