Please I need help on this

Elodia [21]

Step 1. Simplify 10/3b to 10b/3
12/5(10b/3 + 15/4)
Step 2. Distribute
8b + 9

7 0

3 years ago

An instructor in a college class recently gave an exam that was worth a total of 100 points. The instructor inadvertently made t

solniwko [45]

Answer:

B) Method 2 will increase the standard deviation of the students' scores.

Step-by-step explanation:

Given that an instructor in a college class recently gave an exam that was worth a total of 100 points.

The average score for his students was 43 and the standard deviation of the scores was 5 points.

And now he is considering two different strategies for rescaling the exam results of which:

Method 1 = Add 17 points to everyone's score.

Method 2 = Multiply everyone's score by 1.7 .

And we have to check what will be the impact of these methods on the standard deviation of the students' scores.

For this let us consider a simple example to understand this:

Firstly, Formula for calculating Standard Deviation = $\sqrt{\frac{\sum (X-Xbar)^{2}}{n-1}}$

Suppose,

X X - Xbar $(X - Xbar)^{2}$

3 3 - 6 = -3 -3 * -3 = 9

5 5 - 6 = -1 -1 * -1 = 1

10 10 - 6 = 4 4 * 4 = 16

Mean of above data, Xbar = $\frac{3+ 5+10}{3}$ = 6

Standard Deviation of data = $\sqrt{\frac{26}{3-1} }$ = 3.6055

Now let us suppose that we multiply each value of above data with 2 so the new data will be:

X X - Xbar $(X - Xbar)^{2}$

3*2 = 6 6 - 12 = -6 -6 * -6 = 36

5*2 = 10 10 - 12 = -2 -2 * -2 = 4

10*2 =20 20 - 12 = 8 8 * 8 = 64

Mean of new data, Xbar = $\frac{6+ 10+20}{3}$ = 12

Standard Deviation of new data = $\sqrt{\frac{104}{3-1} }$ = 7.2111

Hence, we see that when we multiply any value to the data the standard deviation will increase and in other words it will multiplied by that value which value we multiplied with each data value i.e. when we multiply each data value with 2 the standard deviation also get multiplied by as

3.6055 * 2 = 7.2111

Therefore option B is correct that Method 2 will increase the standard deviation of the students' scores.

And on the other hand Similarly by adding any constant to the data the Standard Deviation will remain same. Therefore Method 1 will have no impact on standard deviation of the students' scores.

8 0

4 years ago

Steffie makes a scale drawing for a crate with the demensions 15 inches long by 12 inches wide. Her scale factor is 1:3. Brian m

rodikova [14]

Answer:

Dimensions → (5 inches × 4 inches)

Step-by-step explanation:

Scale factor used for the drawing by Steffie = $\frac{1}{3}$

Since, scale factor = $\frac{\text{Dimension of the drawing}}{\text{Actual dimension}}$

For Steffie,

Actual length of the crate = $\frac{\text{Dimension of the drawing}}{\text{Scale factor}}$

= $\frac{15}{\frac{1}{3}}$

= 45 inches

Actual width of the crate = $\frac{12}{\frac{1}{3} }$

= 36 inches

Since Brian used the scale factor = $\frac{1}{9}$

Length of the drawing = Actual length × Scale factor

= 45 × $\frac{1}{9}$

= 5 inches

Width of the drawing = Actual width × Scale factor

= 36 × $\frac{1}{9}$

= 4 inches

Therefore, dimensions of the drawing made by Brian are (5 inches × 4 inches)

6 0

3 years ago

I Like a Girl What Do I do?

Natalija [7]

Make her feel important and good about herself. Compliment her, never put her down, and always encourage her to reach for the things she wants. Let her know when you see her do something well, even if it's just something small like helping someone else.

6 0

3 years ago

Read 2 more answers

In class 6, 80percent of the children like crisps.

dezoksy [38]

80% like crisps
75% of the 80% like chocolate.

What percent of the total are the children who like chocolate and crisps?

75% of 80% = 60%

This 60% of children like chocolate and crisps

6 0

4 years ago

Read 2 more answers