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3 years ago

14

a President Bush international and 2005 the newspapers headlines started about four thousand million people in it in the newspap

er rounded to the nearest thousand and what what is the largest number in the smallest number of people who couldn't have been there

1 answer:

svlad2 [7]3 years ago

4 0

The smallest would be 400,000 and the largest would be the same because 0 can't round up or down

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Two catalysts may be used in a batch chemical process. Twelve batches were prepared using catalyst 1, resulting in an average yi

aalyn [17]

Answer:

a) $t=\frac{(91-85)-(0)}{2.490\sqrt{\frac{1}{12}}+\frac{1}{15}}=6.222$

$df=12+15-2=25$

$p_v =P(t_{25}>6.222) =8.26x10^{-7}$

So with the p value obtained and using the significance level given $\alpha=0.01$ we have $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis.

b) $(91-85) -2.79 *2.490 \sqrt{\frac{1}{12} +\frac{1}{15}} =3.309$

$(91-85) +2.79 *2.490 \sqrt{\frac{1}{12} +\frac{1}{15}} =8.691$

Step-by-step explanation:

Notation and hypothesis

When we have two independent samples from two normal distributions with equal variances we are assuming that

$\sigma^2_1 =\sigma^2_2 =\sigma^2$

And the statistic is given by this formula:

$t=\frac{(\bar X_1 -\bar X_2)-(\mu_{1}-\mu_2)}{S_p\sqrt{\frac{1}{n_1}}+\frac{1}{n_2}}$

Where t follows a t distribution with $n_1+n_2 -2$ degrees of freedom and the pooled variance $S^2_p$ is given by this formula:

$\S^2_p =\frac{(n_1-1)S^2_1 +(n_2 -1)S^2_2}{n_1 +n_2 -2}$

This last one is an unbiased estimator of the common variance $\sigma^2$

Part a

The system of hypothesis on this case are:

Null hypothesis: $\mu_2 \leq \mu_1$

Alternative hypothesis: $\mu_2 > \mu_1$

Or equivalently:

Null hypothesis: $\mu_2 - \mu_1 \leq 0$

Alternative hypothesis: $\mu_2 -\mu_1 > 0$

Our notation on this case :

$n_1 =12$ represent the sample size for group 1

$n_2 =15$ represent the sample size for group 2

$\bar X_1 =85$ represent the sample mean for the group 1

$\bar X_2 =91$ represent the sample mean for the group 2

$s_1=3$ represent the sample standard deviation for group 1

$s_2=2$ represent the sample standard deviation for group 2

First we can begin finding the pooled variance:

$\S^2_p =\frac{(12-1)(3)^2 +(15 -1)(2)^2}{12 +15 -2}=6.2$

And the deviation would be just the square root of the variance:

$S_p=2.490$

Calculate the statistic

And now we can calculate the statistic:

$t=\frac{(91-85)-(0)}{2.490\sqrt{\frac{1}{12}}+\frac{1}{15}}=6.222$

Now we can calculate the degrees of freedom given by:

$df=12+15-2=25$

Calculate the p value

And now we can calculate the p value using the altenative hypothesis:

$p_v =P(t_{25}>6.222) =8.26x10^{-7}$

Conclusion

So with the p value obtained and using the significance level given $\alpha=0.01$ we have $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis.

Part b

For this case the confidence interval is given by:

$(\bar X_1 -\bar X_2) \pm t_{\alpha/2} S_p \sqrt{\frac{1}{n_1} +\frac{1}{n_2}}$

For the 99% of confidence we have $\alpha=1-0.99 = 0.01$ and $\alpha/2 =0.005$ and the critical value with 25 degrees of freedom on the t distribution is $t_{\alpha/2}= 2.79$

And replacing we got:

$(91-85) -2.79 *2.490 \sqrt{\frac{1}{12} +\frac{1}{15}} =3.309$

$(91-85) +2.79 *2.490 \sqrt{\frac{1}{12} +\frac{1}{15}} =8.691$

7 0

3 years ago

Solve the equation <br> -3 2/3+b = 8 1/5<br><br> B= 5 3/5<br> B= 4 4/5<br> B= 11 3/5<br> B= 11 1/5

Readme [11.4K]

Answer:

11 13/15

Step-by-step explanation:

-3 2/3+b = 8 1/5

Add 3 2/3 to each side

-3 2/3 + 3 2/3+b = 8 1/5+ 3 2/3

b = 8 1/5 + 3 2/3

We need to get a common denominator of 15

8 1/5 = 8 3/15

3 2/3 = 3 10/15

----------------

11 13/15

4 0

3 years ago

Kaylee put a rectangular sticker on her notebook. The sticker is 1 inch wide and 5 inches long. What area of the notebook does t

kati45 [8]

Answer:

5

Step-by-step explanation:

The area of a rectangle is given by base x height = 1 x 5 = 5

6 0

3 years ago

Find the ratio a:b, if 2a−b/6 = b/3

Tom [10]

Answer:

a:b = 2

Step-by-step explanation:

Here we need to operate with terms in order to arrive to a ratio a:b (or a/b).

We have:

2a−b/6 = b/3

Lets sum b/6 in both sides:

2a−b/6 + b/6 = b/3 + b/6

2a = b/3 + b/6

Now, we can multiply and divide b/3 by 2 to make a 6 appear on the denominator and sum it with b/6, this is, use common denominator:

2a = b/3*(2/2) + b/6

2a = 2b/6 + b/6

2a = 3b/6

2a = b/2, as 3/6 = 1/2

Now lets divide both sides by b to make an a/b appear:

2a/b = (b/2)/b

2a/b = 1/2

Finally, multiply both sides by (1/2) or divide by 2:

(2a/b)/2 = 2

a/b = 2

This is, a is twice as b. If b is 1 so a is 2; if b is 45 so a is 90, and so on.

7 0

4 years ago

Sergio [31]

Answer:

The cost of bicycle is Rs1000

Step-by-step explanation:

Let x be the cost of bicycle

Total profit gained by the shopkeeper by selling at labelled price = 20%

Suppose he sell the bicycles at at 5% discount

Which means that the total profit he learn after discount will be:

20% -5% = 15%

The shopkeeper earns a profit of 15% if he sells at discount.

Profit gained by shopkeeper is:

15% of x = 15/100 · x

15% of x = 0.15x

Thus the profit gained will be 0.15x. As profit gained is equal to 150, we can say that

0.15x = 150

x = 1000

The cost of bicycle is Rs1000

4 0

3 years ago