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3 years ago

If an atom has 5 protons, 7 neutrons and 5 electrons what is the mass number of the atom?

Mathematics

1 answer:

Mariana [72]3 years ago

5 0

Answer:

7+5=12

Step-by-step explanation:

To calculate the mass number of an atom, you have to add the protons and the neutrons. We have 7 neutrons and 5 protons, so your mass number would be 12. Let me know if you have any further questions. :)

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Please help fast, thanks.

Sav [38]

Answer:

b > 100

Step-by-step explanation:

3 0

3 years ago

The gross weekly sales at a certain restaurant are a normal random variable with mean $2200 and standard deviation $230.What is

Lesechka [4]

Answer:

a) The total gross sales over the next 2 weeks exceeds $5000 is 0.0321.

b) The weekly sales exceed $2000 in at least 2 of the next 3 weeks is 0.9033.

Step-by-step explanation:

Given : The gross weekly sales at a certain restaurant are a normal random variable with mean $2200 and standard deviation $230.

To find : What is the probability that

(a) the total gross sales over the next 2 weeks exceeds $5000;

(b) weekly sales exceed $2000 in at least 2 of the next 3 weeks? What independence assumptions have you made?

Solution :

Let $X_1$ and $X_2$ denote the sales during week 1 and 2 respectively.

a) Let $X=X_1+X_2$

Assuming that $X_1$ and $X_2$ follows same distribution with same mean and deviation.

$E(X)=E(X_1+X_2)=E(X_1)+E(X_2)$

$E(X)=2\mu = 2(220)=4400$

$\sigma_X=\sqrt{var(X_1+X_2)}$

$\sigma_X=\sqrt{2\sigma^2}$

$\sigma_X=\sqrt{2}\sigma$

$\sigma_X=230\sqrt{2}$

So, $X\sim N(4400,230\sqrt{2})$

$P(X>5000)=1-P(X\leq5000)$

$P(X>5000)=1-P(Z\leq\frac{5000-4400}{230\sqrt{2}})$

$P(X>5000)=1-P(Z\leq1.844)$

$P(X>5000)=1-0.967$

$P(X>5000)=0.0321$

The total gross sales over the next 2 weeks exceeds $5000 is 0.0321.

b) The probability that sales exceed teh 2000 and amount in at least 2 and 3 next week.

We use binomial distribution with n=3.

$P(X>2000)=1-P(X\leq2000)$

$P(X>2000)=1-P(Z\leq\frac{2000-2200}{230})$

$P(X>2000)=1-P(Z\leq-0.87)$

$P(X>2000)=1-0.1922$

$P(X>2000)=0.808$

Let Y be the number of weeks in which sales exceed 2000.

Now, $P(Y\geq 2)$

So, $P(Y\geq 2)=P(Y=2)+P(Y=3)$

$P(Y\geq 2)=^3C_2(0.8077)^2\cdot (1-0.8077)+^3C_3(0.8077)^3$

$P(Y\geq 2)=0.37635+0.52692$

$P(Y\geq 2)=0.90327$

The weekly sales exceed $2000 in at least 2 of the next 3 weeks is 0.9033.

3 0

3 years ago

Solve for z. 5z − 6 − 34 = zz − 6

valkas [14]

Answer:

$z=\frac{17}{2}$

Step-by-step explanation:

5z-6-34=z-6

combine like terms (-6-34)

5z-40=z-6

subtract z on both sides

5z-z-40=-6

4z-40=-6

add -40 on both sides

4z=34

divide both sides by 4

$\frac{4z}{4}=\frac{34}{4}$

z= $\frac{17}{2}$

hope this helps

7 0

3 years ago

Help i need asaaaaaap °∠°

lawyer [7]

Answer:

Cube 1 = 30 cubic

Cube 2 = 48 cubic

Cube 3 = 72 cubic

Step-by-step explanation:

Cube 1 = 5x2x3

Cube 2 = 6x2x4

Cube 3 = 8x3x3

8 0

3 years ago

Maya had $27. She spent all the money on buying 3 burgers for $x each and 2 sandwiches for $y each. If Maya had bought 2 burgers

SIZIF [17.4K]

Anything that is close to.

Because $27- 3*$5 - 2*6 = 0 and $5*2 +1 *$6 = $16, $27-$16 = $11 left over. I can make a system of equations to prove that this is the correct answer.

6 0

3 years ago