# Tutor profile: Andrew P.

## Questions

### Subject: Pre-Algebra

Hi I would like help with the following question. The data below shows the average age of students. Find the mean, median and mode of the data. Would the mean or median be better used to describe the data and why? 10, 14, 15, 15, 16, 13

Hi The mean is the the average of the data. To find the mean you add all the numbers then divide by the total. Mean = (10 + 14 + 15 + 15 + 16 + 13) divided by 6 = 13.83 years. The median is another type of average. To find the median you arrange the numbers from smallest to biggest then you cross of the ends. Median = 10, 13, 14, 15, 15, 16. By crossing off both ends at once you get 13, 14, 15, 15. Then we get 14, 15. Since we are left with two numbers we add then divide by 2 to get the median. The median is 14.5 The mode is the number that occurs the most often. Here 15 occurs twice and that is the most often. Therefore the mode is 15. Since there is no outlier in this set the data the mean would describe the data better.

### Subject: Physics

Hi I need help with the following question. A circuit has 2 resistors of value 3ohm and 5ohm that are connected in series. The internal resistance of the circuit is 2ohm. What is the emf of the circuit if the current is 5A?

Hi When solving any physics problem you always want to start with the data. The data takes the word problem and translates it to values then you can solve it. So from the problem the the circuit has 2 resistors each are 3ohm and then 5ohm. So for the data we write the variable that each is and then the value always with the units. So since a resistor measures resistance then R1 would be 3ohm and R2 would be 5ohm because R is the variable for resistance. Then the internal resistance is 2ohm so r would be 2ohm. The current is 5A so I would be 5A. Then the question wants to find the emf so e = ?. We put a question mark with the unknown. Data R1 = 3ohm R2 = 5ohm r = 2 I = 5A emf = ?? Now that we have our data the next step is the solution. So we choose a formula and then solve. To solve we need our formula to have only one unknown. The formula here I = emf divided by (R + r). We next to need to make sure the units are in SI units and if not convert. Here the units are good. Also here since we have 2 resistors we need to find the equivalent resistance. Since they are in series that is just R = R1 + R2 and so the equivalent resistance is R = 3 + 5 = 8. The next step is to put the values into the the formula and then solve. We then get 5 = e divided by (8 + 2). We then get 5 = e/10. We multiply both sides by 10 and get e = 50V. The answer is emf = 50V. We always include the unit at the end.

### Subject: Algebra

Hi I would like help finding 3x - y in the following equations: 2x + y = 9 and then x - 3y = 20

Hi There So remember to solver for 2 variable we need two equations and we have that here. So the first step in these problems is to solve one of the equations for one variable. It doesn't matter and often times there is an easy choice. So here we will solve the second equation for x by adding 3y to both sides. We add because when solving for variables we want to undo the subtraction. That gives us x = 20 + 3y. Now that we have solved for x we plug that value into the other equation. We then get 2(20 + 3y) + y = 9. Then we simplify and get 40 + 6y + y = 9. Next we add the 6y and y to get 40 + 7y = 9. Now to find y we subtract the 40 because subtraction undoes addition and get 7y = -31. Next to find y we divide by 7 because we want to get y all by itself and division will undo multiplication. We then get y = -4.42. Now that we found y we plug that value back into the first equation to find x. So we get x = 20 + 3(-4.42). We get x = 6.74. Since the question asks to find 3x - y we put in for x and y and then do the math. So we get 3(6.74) - (-4.42) and that gives us 24.64

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