All categories

3 years ago

Simplify the following expressions and remember to pay attention to the signs plz help me

Mathematics

2 answers:

ioda3 years ago

7 0

2 negatives can be converted to a plus sign. -(-x) can be +x or just x.

-54--23

-54+23

23-54=-31

78--4

78+4=82

-48/-6

Now let's pause fer a sec. When a negative is being divided by another negative, the quotient(answer to division problem) becomes a positive.

-48/-6=8

50*-4=-200

---

hope it helps

baherus [9]3 years ago

6 0

Answer:

1)-31

2)82

3)8

4)-200

Step-by-step explanation:

I have checked and verified these

You might be interested in

Cot^2 x- 6cotx - 5=0

viva [34]

Step-by-step explanation:

cotx=t

t^2-6t-5=0

t=cotx=1or5

3 0

3 years ago

on monday two hundred thirty-four students went on a trip to the zoo. All five buses were filled and four students had to travel

Fofino [41]

Answer: 46 students on each bus

Step-by-step explanation:

234-4=230

230/5=46

3 0

3 years ago

Researchers are interested in the effect of a certain nutrient on the growth rate of plant seeding. Use a hydroponics grow proce

Rashid [163]

Answer:

The 95% confidence interval for the mean would be given by (56.604;68.596)

The 99% confidence interval for the mean would be given by (53.196;72.004)

Step-by-step explanation:

1) Previous concepts

When we compute a confidence interval for the mean, we are interested on the parameter population mean, and we use the info from the sample to estimate this parameter.

2) Basic operations

The sample mean can be calculated with the following formula

$\sum_{i=1}^n \frac{x_i}{n}$

Using excel we can use this function to calculate the mean:

=AVERAGE(54.2,59.8,61.8,63.3,65.1,71.4)

The value obtained is $\bar X=62.6$

In order to find the sample deviation we can use this formula

$s=\sqrt{\sum_{i=1}^n \frac{(x_i-\bar X)^2}{n-1}}$

And using excel we can use this function to calculate the sample standard deviation:

=STDEV.S(54.2,59.8,61.8,63.3,65.1,71.4)

The value obtained is $s=5.713$

The sample size for this case is n=6, n<30 so then is better use the t distribution to calculate the margin of error. First we need to calculate the degrees of freedom, on this case $df=n-1=6-1=5$

The formula for the confidence interval would be given by:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

3) Part a

If we want a 95% or 0.95 of confidence, then the value for the signficance is $\alpha=1-0.95=0.05$ , and $\alpha/2=0.025$ , and $1-\frac{\alpha}{2}=0.975$ so we can find the critical t value with the following formula in excel:

=T.INV(0.975,5)

And we got $t_{\alpha/2}= 2.571$

And we can replace into equation (1) and we got:

$62.6 \pm 2.571\frac{5.713}{\sqrt{6}}$

And using excel with the following formulas we got:

=62.6-2.571*(5.713/SQRT(6)) = 56.604

=62.6+2.571*(5.713/SQRT(6)) = 68.596

So the 95% confidence interval for the mean would be given by (56.604;68.596)

4) Part b

If we want a 99% or 0.99 of confidence, then the value for the signficance is $\alpha=1-0.99=0.01$ , and $\alpha/2=0.005$ , and $1-\frac{\alpha}{2}=0.995$ so we can find the critical t value with the following formula in excel: