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3 years ago

I need help...cause i’m confused

Mathematics

1 answer:

Arisa [49]3 years ago

6 0

the answer is d thats what im choosing because i recall doing a similar problem to this

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Isotope ⁷⁹br has an abundance of 50.69%

Simora [160]

Answer:

79.986

Step-by-step explanation:

Let A represent isotope ⁷⁹Br

Let B represent isotope ⁸¹Br

From the question given above, the following data were obtained:

For Isotope A (⁷⁹Br):

Mass of A = 79

Abundance of A (A%) = 50.69%

For isotope B (⁸¹Br):

Mass of B = 81

Abundance of B (B%) = 49.31%

Relative atomic mass of Br =?

The relative atomic mass (RAM) of Br can be obtained as follow:

RAM = [(Mass of A × A%) /100] + [(Mass of B × B%) /100]

= [(79 × 50.69) /100] + [(81 × 49.31) /100]

= 40.0451 + 39.9411

= 79.986 amu

Thus, the relative atomic mass of Br is 79.986

5 0

3 years ago

Reese is selling lemonade at the parade. He gets to keep 30% of the money he collects. A large lemonade is $4.00 and a small lem

Marysya12 [62]

Answer:0.30(4L)+0.30(2s) Plz mark brainliest.

Step-by-step explanation:

4 0

3 years ago

HELP IMMEDIATELY PLEASE, WILL GIVE BRAINLIEST!!!

egoroff_w [7]

Answer:

The slope is -1/3 I think.

5 0

3 years ago

Read 2 more answers

Suppose you read online that children first count to 10 successfully when they are 32 months old, on average. You perform a hypo

creativ13 [48]

Answer:

$p_v =2*P(t_{(35)}$

Step-by-step explanation:

Assuming this info from R

hist(gifted$count)

## Min. 1st Qu. Median Mean 3rd Qu. Max.

## 21.00 28.00 31.00 30.69 34.25 39.00

## Sd

## [1] 4.314887

Data given and notation

$\bar X=30.69$ represent the mean

$s=4.3149$ represent the sample standard deviation

$n=36$ sample size

$\mu_o =32$ represent the value that we want to test

$\alpha$ 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 mean is different than 32, the system of hypothesis would be:

Null hypothesis: $\mu = 32$

Alternative hypothesis: $\mu \neq 32$

If we analyze the size for the sample is > 30 but we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-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:

$t=\frac{30.69-32}{\frac{4.3149}{\sqrt{36}}}=-1.822$