A national dental association conducted a survey to find the average (mean) amount of time dentists spend on dental fillings per

2.8y + 6 + 0.2y = 5y – 14

Start by simplifying the left side:

3y + 6 = 5y - 14

Next, deduct 3y from both sides:

6 = 2y - 14

Add 14 to both sides:

2y = 20

Now, divide by 2:

y = 20 / 2

y = 10

Step-by-step explanation:

The difference quotient represents the slope of the line connecting two points on a curve. To achieve the most accurate estimate, we need to use points that are nearest to x = 0. For this problem, the relevant points are (-0.001, 1.999) and (0.001, 2.001).

m = (2.001 − 1.999) / (0.001 − (-0.001))

m = 1

Answer:

a) In this case, we have a z-score of 1.57, characterized as:

This signifies that our score is 1.57 standard deviations above the average of all test scores.

b)

Using the normal standard distribution or Excel, we computed:

This represents 2.275% of the dataset.

Step-by-step explanation:

Previous concepts

Normal distribution denotes a "probability distribution that is symmetric around the mean, indicating that data close to the mean occurs more frequently than data further from it".

The Z-score serves as "a statistical measurement representing a value's relation to the average (mean) of a set, calculated in terms of standard deviations away from the mean".

Solution to the problem

Part a

For this instance, we hold a z-score of 1.57, which is defined as:

This shows that our score is 1.57 deviations above the overall test score average.

Part b

A z-score of z=-2 indicates that your friend's score is 2 deviations below the other test scores.

Assuming a normal distribution, we can derive the percentage:

Using the normal standard distribution or Excel, we discovered:

This represents 2.275% of the data.