Word Problems

Question 1

What is the equation for simple interest?

Answer 1

SI = (PRT)/100

A = P + SI

P = Principal, R = Rate, T = Time, A = Amount

Question 2

What is the equation for compound interest?

Answer 2

A = P (1+(r/n))^(nt)

so if rate 8% - r = 8/100, interest is quarterly and period is 2 years so n = 4, t =2

Question 3

How do you calculate work rate of elements in opposition?

Answer 3

Relative rate is the positive difference
i.e. RA - RB

Question 4

What is the equation definition for work?

Answer 4

Rate = Work/Time

Question 5

How do you calculate rates when two elements work:
1. Simultaneously
2. In sequence

Answer 5

1. R = R1 + R2 +…
2. T = T1 + T2 + …

Question 6

Markup = ?

Answer 6

Marked Price - Cost Price

Question 7

Profit = ?

Answer 7

Sale Price - Cost Price

Question 8

Discount = ?

Answer 8

Sale Price - Marked Price

Question 9

What is the equation if:
1. x is p% more than y
2. x is p% less than y

Answer 9

1. x = y (1 + p/100)
2. x = y (1 - p/100)

Question 11

What is the impact on the 1. standard deviation 2. variance if you multiply or divide all the data points in a set by the same number, n?

Answer 11

1) sd2 = n.(sd1), sd2 = (sd1)/n
2) var2 = (nˆ2).(var1), var2 = (var1)/(nˆ2)

Question 12

What is the impact on 1) standard deviation, 2) variance if you add or subtract the same number, n, from all of the data points in a set?

Answer 12

1) sd2 = sd1
2) var2 = var1
The spread has not changed

Question 13

What is the equation for the variance of a set from the mean?

Question 14

What does standard deviation tell us?

Answer 14

The spread of the data set about the mean

Question 15

What does it mean if a data set has a:
1) High standard deviation
2) Low standard deviation

Answer 15

1) The data set has elements far from the mean i.e. it has a large spread
2) The data set has elements closer to the mean i.e. it has a narrow spread

Question 16

What is the equation for standard deviation?

Question 17

What do the following words mean?
1) bimodal
2) trimodal
3) multimodal

Answer 17

1) The set has 2 modes i.e. 2 numbers that have the same, highest frequency
2) The set has 3 modes
3) The set has more than 3 modes

Question 18

How do you find the median for a set with an even number of elements?

Answer 18

Median is the = ((n) + (n+1)/2) / 2) th number

Question 19

How do you find the median for a data set with an odd number of elements?

Answer 19

The median is the (n+1) /2 th value

Question 20

What is the impact on the mean if one data point is added where:
1) xi < mean
2) xi > mean
3) xi = mean

Answer 20

1) mean decreases
2) mean increases
3) mean is the same

Question 21

What is the impact on the mean of a data set when any operation (+, -, /, x) is applied to all elements of a data set?

Answer 21

The same operation is applied to the mean

Question 22

What is the equation to find a weighted mean?

Answer 22

Weighted mean = (Sum(xi.wi)) / (Sum of wi)

Question 23

What is the relationship between the mean and the median when the data sets are evenly spaced?

Answer 23

They are the same

Question 24

What is the equation to find the mean?