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slega [8]
2 years ago
14

A pond had 60 fish. 27 were carp and the rest were tench. 10 fish were added. The probability that a fish picked at random is a

carp is now 1/2 how many tench were added?
Mathematics
1 answer:
ivanzaharov [21]2 years ago
6 0

Answer: 2

<u>Explanation:</u>

A pond had 60 fish but 10 were added so now the pond has 70 fish.

The probability of choosing a carp is 1/2 so \frac{1}{2} (70) = 35 are now carp.  

There were 27 carp and now there are 35 carp so 8 carp were added.

10 fish were added and 8 of them were carp so 2 of them were tench.

You might be interested in
Jenny is taking a vacation to Florida. She travels 70 kilometers per hour for 2 hours, and 63 kilometers per hour for 5 hours. O
Helga [31]
Jenny traveled 70 km/h over 2 hours and 63 km/h over 5 hours. Her travel time was a total of 7 hours. 

We need to find out how far she traveled during this 7-hour period.

70 km/h * 2 h = 140 km 
63 km/h * 5 h = 315 km

Then, we can add 140 km and 315 km to get a total distance traveled of <em>455 km/h.</em>

We were asked to find the average <em>speed.</em> We can find it now, since we have total distance traveled (455 km) and total time taken (7 hours).

Then, 
455km / 7h = 65 km/h.
6 0
2 years ago
A member of a student team playing an interactive marketing game received the fol- lowing computer output when studying the rela
nirvana33 [79]

Answer:

p_v = 2*P(t_{n-2} > |t_{calc}|)= 0.91

So on this case for the significance level assumed \alpha=0.05 we see that p_v >\alpha so then we can conclude that the result is NOT significant. And we don't have enough evidence to reject the null hypothesis.

So on this case is not appropiate say that :"the more we spend on advertising this product, the fewer units we sell" since the slope for this case is not significant.

Step-by-step explanation:

Let's suppose that we have the following linear model:

y= \beta_o +\beta_1 X

Where Y is the dependent variable and X the independent variable. \beta_0 represent the intercept and \beta_1 the slope.  

In order to estimate the coefficients \beta_0 ,\beta_1 we can use least squares procedure.  

If we are interested in analyze if we have a significant relationship between the dependent and the independent variable we can use the following system of hypothesis:

Null Hypothesis: \beta_1 = 0

Alternative hypothesis: \beta_1 \neq 0

Or in other words we want to check is our slope is significant (X have an effect in the Y variable )

In order to conduct this test we are assuming the following conditions:

a) We have linear relationship between Y and X

b) We have the same probability distribution for the variable Y with the same deviation for each value of the independent variable

c) We assume that the Y values are independent and the distribution of Y is normal  

The significance level assumed on this case is \alpha=0.05

The standard error for the slope is given by this formula:

SE_{\beta_1}=\frac{\sqrt{\frac{\sum (y_i -\hat y_i)^2}{n-2}}}{\sqrt{\sum (X_i -\bar X)^2}}

Th degrees of freedom for a linear regression is given by df=n-2 since we need to estimate the value for the slope and the intercept.  

In order to test the hypothesis the statistic is given by:

t=\frac{\hat \beta_1}{SE_{\beta_1}}

The p value on this case would be given by:

p_v = 2*P(t_{n-2} > |t_{calc}|)= 0.91

So on this case for the significance level assumed \alpha=0.05 we see that p_v >\alpha so then we can conclude that the result is NOT significant. And we don't have enough evidence to reject the null hypothesis.

So on this case is not appropiate say that :"the more we spend on advertising this product, the fewer units we sell" since the slope for this case is not significant.

3 0
2 years ago
Suppose 1000 people enter a chess tournament. Use a rooted tree model of the tournament to determine how many games must be play
Vlada [557]

Answer: 999 games

Step-by-step explanation:

There are many ways to illustrate the rooted tree model to calculate the number of games that must be played until only one player is left who has not lost.

We could go about this manually. Though this would be somewhat tedious, I have done it and attached it to this answer. Note that when the number of players is odd, an extra game has to be played to ensure that all entrants at that round of the tournament have played at least one game at that round. Note that there is no limit on the number of games a player can play; the only condition is that a player is eliminated once the player loses.

The sum of the figures in the third column is 999.

We could also use the formula for rooted trees to calculate the number of games that would be played.

i=\frac{l - 1}{m - 1}

where i is the number of "internal nodes," which represents the number of games played for an "<em>m</em>-ary" tree, which is the number of players involved in each game and l is known as "the number of leaves," in this case, the number of players.

The number of players is 1000 and each game involves 2 players. Therefore, the number of games played, i, is given by

i=\frac{l - 1}{m - 1} = i=\frac{1000 - 1}{2 - 1} = \frac{999}{1} =999

7 0
1 year ago
Write the coordinates of the vertices after a rotation of 180 degrees counterclockwise around the origin.
Umnica [9.8K]

90 degrees you are looking to your side

180 degrees you are looking behind you

around origin of 0,0

the image is flipped into the negative world if it is in posiitve or vice versa

8 0
2 years ago
Between 1896—when the Dow Jones index was created— and 2012, the index rose in 65% of the years. Based on this information, and
forsale [732]

Answer:

a) P(x) = 0.67

b)  P(y) = 0.67

c) P(x=4) = 0.3325

d) P( x = 0 ) = 0.0039

e) The fact that the rise and fall of the stock market relies on market sentiments violates independence used in Binomial distribution and the years are independent

Step-by-step explanation:

A) The probability that the stock market will rise next year = P(x) = 0.67

assuming next year to be X

B) Probability that the stock market will rise the year after next year

= P(y) = 0.67 and this is because the probability is independent of that of the previous years

C) Probability that the stock market will rise in four of the next five years

= P(x=4) = 0.3325

D) probability that the stock market will rise in none of the next five years

= P( x = 0 ) = 0.0039

E) The fact that the rise and fall of the stock market relies on market sentiments violates independence used in Binomial distribution and the years are independent

4 0
2 years ago
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