Arithmetic reasoning Flashcards
Average
Standard deviation
Arithmetic mean
Take the sum of n numbers and divide by n
1
[Population] Standard deviation = sqrt (— sum(xi - xbar)^2)
N
1 Sample Standard deviation = sqrt(—— sum(xi - xbar)^2) (N-1)
1 mi = ? ft
1mi = 5,280 ft
Median of odd # of Data
The middle # if the data is listed in increasing order.
Median of an even # of data
Arithmetic mean (average) of the two middle numbers when the data is listed in increasing order.
Mode
Most frequently occurring # in the list. There may be more than one mode for a list of data
Range
Greatest # in the list - least #
Interquartile range
3rd quartile - 1st quartile To divide data into quartiles: 1) arrange in increasing order 2)find median M. M = Q2 3) divide data into 2 equal groups, find their median, it is Q1 and Q3
x + y = -1
Quantity A QuantityB
x y
One equation, 2 unknowns,
D) the relationship cannot be determined from the information given.
Can also plug in
x = 0
Then
y = 0
A certain store sells two types of pens: one type for $2 per pen and the other type for $3 per pen. If a customer can spend up to $25 to buy pens at the store and there is no sales tax, what is the greatest # of pens the customer can buy?
Start by looking at how many of the lesser value, $2, pens the customer can buy if the customer doesn’t buy any $3 pens.
25/2 = 12.5 .
So 12 pens for $2, 0 pens for $3.
Next consider $3 pens
11 $2 pens ($22) and 1 $3 pen = 12 pens total
10 $2 pens ($20) and 1 $3 pen = 11 pens total
9 $2 pens ($18) and 2 $3 pen= 11 pens total.
As the # of $2 pens decreases the total # of pens decreases.
Therefore max amount = 12 pens
A list of numbers has a mean of 8 and standard deviation of 2.5. If x is a # in the list that is 2 standard deviations above the mean, what is the value of x?
x = 2(2.5) + 8 x = 13
The following table shows the distribution of 200,000 physicians by specialty. Which of the following sectors represent more than 40,000 physicians?
A. Pediatrics - 21% B. Internal Medicine - 25% C. Surgery - 24% D. Anesthesiology - 3% E. Psychiatry - 6%
Find what percent of 200,000 is 40,000
40,000/200,000 = 0.2 = 20%
choices over 20% are A, B, C.
Profit
Profit, or gross profit = sales revenue - cost of production
If n is the integer, what is the sum of first two consecutive integers greater than n + 6?
(n+7)+(n+8)
In 2009 the property tax on each home in Town X was p percent of the assessed value of the home, where p is a constant. The property tax in 2009 on a home in Town X that had an assessed value of $125, 000 was $2, 500
Quantity A QuantityB
The property tax in 2009 on $3,000
a home in Town X that had
an assessed value of
$160, 000
$125,000p = $2,500 P = 125000/2500 P = 0.02 or 2%
2% of $160,000 is
160,000 * 0.02 = 3,200
3,200 > 3000
A>B
Congruent angles
Angles that have equal measures. Opposite angles
Acute angle
Less than 90 degrees
Obtuse angle
Angle b/w 90 and 180 degrees
Convex polygon
A polygon in which the measure of each interior angle is less than 180 degrees
Sum of interior angles of a polygon
(n-2)*180
Sum of hexagon (6-2)180=720
Regular polygon
A polygon in which all sides are congruent and all interior angles are congruent.
Quadrilateral
4 sided polygon
Equilateral triangle
Triangle with three congruent sides
Isosceles triangle
A triangle with at least two congruent sides
Congruent triangles
Two triangles that have the same shape and size
Similar triangles
Two triangles that have the same shape but not the same size
Area of a parallelogram
Same as area of a square or rectangle or any quadrilateral.
Area = base* height