Word Problems Flashcards
What is the equation for simple interest?
SI = (PRT)/100
A = P + SI
P = Principal, R = Rate, T = Time, A = Amount
What is the equation for compound interest?
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
How do you calculate work rate of elements in opposition?
Relative rate is the positive difference
i.e. RA - RB
What is the equation definition for work?
Rate = Work/Time
How do you calculate rates when two elements work:
1. Simultaneously
2. In sequence
- R = R1 + R2 +…
- T = T1 + T2 + …
Markup = ?
Marked Price - Cost Price
Profit = ?
Sale Price - Cost Price
Discount = ?
Sale Price - Marked Price
What is the equation if:
1. x is p% more than y
2. x is p% less than y
- x = y (1 + p/100)
- x = y (1 - p/100)
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?
1) sd2 = n.(sd1), sd2 = (sd1)/n
2) var2 = (nˆ2).(var1), var2 = (var1)/(nˆ2)
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?
1) sd2 = sd1
2) var2 = var1
The spread has not changed
What is the equation for the variance of a set from the mean?
What does standard deviation tell us?
The spread of the data set about the mean
What does it mean if a data set has a:
1) High standard deviation
2) Low standard deviation
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
What is the equation for standard deviation?
What do the following words mean?
1) bimodal
2) trimodal
3) multimodal
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
How do you find the median for a set with an even number of elements?
Median is the = ((n) + (n+1)/2) / 2) th number
How do you find the median for a data set with an odd number of elements?
The median is the (n+1) /2 th value
What is the impact on the mean if one data point is added where:
1) xi < mean
2) xi > mean
3) xi = mean
1) mean decreases
2) mean increases
3) mean is the same
What is the impact on the mean of a data set when any operation (+, -, /, x) is applied to all elements of a data set?
The same operation is applied to the mean
What is the equation to find a weighted mean?
Weighted mean = (Sum(xi.wi)) / (Sum of wi)
What is the relationship between the mean and the median when the data sets are evenly spaced?
They are the same
What is the equation to find the mean?
