Which is a better buy? 9.30 for 10 sharpies or 6.55 for 7?

Question Details

Sliva [168]

Answer:

Atomic mass unit-

It is represented by ‘amu’. It is equal to the quantity 1/12th mass of an atom of C-12.

Actual mass of one atom of C-12 = 1.9924 x 10-23 gm. = 1.9924 x 10-26 Kg.

1 amu = 1.9924 x 10 -23/12 = 1.66 x 10 -24 gm. = 1.66 x 10 -27 Kg.

Atomic mass of an element = mass of one atom of the element / 1 amu

Actual mass of an element = atomic mass of an element in amu x 1.66 x 10 -24 gm.

For ex-

Actual mass of hydrogen atom = 1.008 x 1.66 x 10 -24 gm. = 1.6736 x 10-24 gm.

Actual mass of oxygen atom = 16.00 x 1.66 x 10 -24 gm. = 2.656 x 10-23 gm.

Average Atomic weight (Mass)-

“The Average Atomic Masses of many elements are determined by multiplying the atomic mass of each isotope by its fractional abundance and adding these values and then dividing it by 100.”

Ex.- Naturally occurring carbon contains three isotopes – C12 (98.892 % abundance), C13 (1.108 % abundance), C14 (2 x 10-10 % abundance).The relative atomic masses of these isotopes are 12.000, 13.00335 and 14.00317 amu respectively.

Average atomic mass = % of I isotope x its atomic mass + % of II isotope x its atomic mass +% of III isotope x its atomic mass/100

= 12 x 98.892 + 13.00335 x 1.108 + 14.00317 x 2 x10-10 /100

Average atomic mass= 12.011 amu

Molar volume –

Molar volume of a substance is volume occupied by 1 mole of that substance .

Molar volume of solid or liquid = molar mass / density

Molar volume of ideal gas at 00C or 273 K and 1 atmosphere pressure is 22.4 litre.

Gram atomic mass(weight) or gram atom –

“Gram atomic mass(weight) of an element is the mass of Avogadro number ( 6.023 x 1023 ) of atoms of that elements in grams.”

Ex –

mass of 1 atom of oxygen = 16 amu = 16 x 1.66 x 10-24 gm

Mass of 6.023 x 1023 atoms of oxygen= 16 x 6.023 x 1023 x 1.66 x 10-24 = 16 gm.

Hence, Gram atomic weight of oxygen = 16 gm.

No. of gram atoms = mass of element in gm / atomic mass of element in gm.

7 0

2 years ago

A random sample of 16 students selected from the student body of a large university had an average age of 25 years. We want to d

kenny6666 [7]

Answer:

$z=\frac{25-24}{\frac{2}{\sqrt{16}}}=2$

$p_v =2*P(Z>2)=0.0455$

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can conclude that the true mean differs from 24 at 5% of significance

Step-by-step explanation:

Data given and notation

$\bar X=25$ represent the sample mean

$\sigma=2$ represent the sample population deviation for the sample

$n=16$ sample size

$\mu_o =24$ represent the value that we want to test

$\alpha=0.05$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the true mean is different from 24, the system of hypothesis would be:

Null hypothesis: $\mu = 24$

Alternative hypothesis: $\mu \neq 24$

If we analyze the size for the sample is < 30 but we know the population deviation so is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{25-24}{\frac{2}{\sqrt{16}}}=2$

P-value

Since is a two sided test the p value would be:

$p_v =2*P(Z>2)=0.0455$

Conclusion

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can conclude that the true mean differs from 24 at 5% of significance

6 0

3 years ago

Write the absolute value equations in the form |x−b|=c (where b is a number and c can be either number or an expression) that ha

nalin [4]

Answer:

i don't know

Step-by-step explanation:

i don't know sorry bud:/

6 0

2 years ago

Rewrite 4x = 64 as a logarithmic equation.

anygoal [31]