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2 years ago

An atom of a certain element has 21 protons, 21

1 answer:

3 0

45-21=24 neutrons :)

As the generally accepted mass of an electron is 0. So, to find the mass of neutrons, minus the protons from the total mass.

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A curious patterns occurs in a group of people who all shake hands with one another. It turns out that you can predict the numbe

ycow [4]

Missing part of the question

Determine the number of handshakes, i, that will occur for each number of people, n, in a particular room. (people)

Answer:

$S_n = \frac{n}{2}(n - 1)$

Step-by-step explanation:

Given

For 5 people

$\begin{array}{cc}{People} & {Handshakes} & {5} & {4} & {4} & {3} & {3} & {2} & {2} & {1} & {1} & {0} &{Total} & {10} \ \end{array}$

Using the given instance of 5 people, the number of handshakes can be represented as:

$(n - 1) + (n - 2) + (n - 3) + ........ + 3 + 2 + 1 + 0$

The above sequence is an arithmetic sequence and the total number of handshakes is the sum of n terms of the sequence.

$S_n = \frac{n}{2}{(T_1 + T_n})$

Where

$T_1 = n - 1$ --- The first term

$T_n = 0$ --- The last term

So:

$S_n = \frac{n}{2}(n - 1 + 0)$

$S_n = \frac{n}{2}(n - 1)$

7 0

2 years ago

A wireless phone company charges a monthly fee of $39.99 plus $0.49 per minute for usage that exceeds the included minutes. Writ

Marizza181 [45]

Answer:

$54.20

Step-by-step explanation:

minute=m

total monthly cost = p

39.99 + .49m = p

39.99 + .49(29) =p

39.99 + 14.21 =p

54.2 =p

3 0

3 years ago

Find the circumference of 21cm

hoa [83]

132cm) so so du Di Di xi Fi vi du du du do go

6 0

3 years ago

Evaluate C = 2 r, for r = 8.

Jet001 [13]

Answer:

C = 16

Step-by-step explanation:

Substitute r = 8 into the equation for C, hence

C = 2r = 2 × 8 = 16

4 0

3 years ago

Read 2 more answers

When a man observed a sobriety checkpoint conducted by a police department, he saw 671671 drivers were screened and 77 were arr

kifflom [539]

Answer:

$P(\overline W)=0.98957$

Step-by-step explanation:

Number of drivers Screened = 671

Number Arrested for Driving While Intoxicating = 7

If the W denotes the event of screening a driver and getting someone who is intoxicated.

The Probability of W, $P(W)=\frac{7}{671}=0.01043$

The Probability $P(\overline W)$ is the probability of the event of screening a driver and getting someone who is not intoxicated. Simply put, it is the Probability of the Complement of W.

From Probability Theorem,

$P(W)+P(\overline W)=1\\Since \: P(W)=0.01043\\0.01043+P(\overline W)=1\\P(\overline W)=1-0.01043\\=0.98957$

8 0

3 years ago