practice problems day 3

algebraic expression of odd integer

(2k+1) or (2k-1)

range

max-min

interquartile range

q3-q1

prob of 0

impossible

14²

196

probability =

#of successes/# of outcomes

15²

225

e*e

e

suppose we start w 5L 30% hcl solution. how much water must we add to create a 20% solution

1. find how much is hcl by conc=x/solution, then take hcl and do new con=hcl/x to get the new liters, then subtract the original liters to get how much water to add

find the gcf of two numbers

1. find prime factorizations 2.look at the highest power of each factor they share 3. multiply those factors

how many factors does 8400 have? how to solve

1. find prime factors 2. list the exponents of the prime factors 3. add one to each exponent 4. multiply the exponents

prob 1=

100% certain

11²

121

12²

144

13²

169

bell curve what is % for 1 and 2 SD

34% 13.5%

how to calculate sd

Step 1: Find the mean. Step 2: For each data point, find the square of its distance to the mean. Step 3: Sum the values from Step 2. Step 4: Divide by the number of data points. Step 5: Take the square root.

Marcia has 2 liters of a 60% concentrated solution of phosphoric acid. She wants to add 3 liters of less concentrated phosphoric acid solutions, so that she has 5 liters of a solution with a concentration less than 50%. Which could she add?

conc equation for first and last to find concentration of solute, then subtract. then conc equation of all answers must be less than the difference

mixture problems

conc=total solute/solution*100

n=135 is the lowest in a set of 11 consecutive multiples of 5. what is the difference between the lowest and highest numbers in the set

doesnt matter which multiples of 5 because they are evenly spaced when they are consecutive. 5*1=5, 5*11=55 so 55-5=50

e*o

e

e+e=

e

e-e=

e

o+o=

e

o-o=

e

if n is an integer greater than 10, then (n²-2n)(n+1)(n-1) must be divisible by: 4 6 18

factor out an n to get a set of 4 consecutive integers. in any 4 integers, they will be divisible by 2 and 3, but not enough 3s to be divisible by 8

List A: {x, x, x, y, y, y, 3x+y, x-y } If the median of list A is 10 and 0 < x < y, what is the range of list A?

figure out the list, it is out of order. then simplify the range equation Highest-lowest, note that x+y=2(10) so you can factor and sub

to count even factors

find odd factors then subtract from all factors

to find the number of odd factors

find prime factors and list exponents ignore factors of 2 and add one to the rest of the exponents multiply the exponents

at a company there are two classes: silver and gold . if there are 160 gold and they make an average of 56,000 higher than silver, and 120 silver, how much higher is the total average than silver

find ratio of g:s, add together, divide salary by added ratio, multiply bigger one by the quotient or multiply percent by salary and add them together

suppose we start w 8 Lof a 60% solut. we add 4 L of c% solut and the result is 12L of .5 solut. what is c?

find solute for 1st and last, then subtract them to get solute for middle, then plug in solute/L to get Con%

LCM ie: 24&32 how to find

find the GCF* whatever number gets you that product multiply the gcf* those numbers GCF=8 24=8*3 32=8*4 LCM=8*3*4

if the median of list b is exactly 4 higher than list a, what is the value of x

find the median of list a+4 list a median+4=x+number under median/2

sd is

how spread out numbers are

lcm =

lcd

in a certain company 70% make 40,000 20% make 80000 and 10% make 120,000. what is the average for all employees

multiply percent by salary and add them together

e+o=

o

e-o=

o

o*o

o

a perfect square always has _ _ of factors

odd number

if all the prime factors of a number have even exponents it is a

perfect square

A box contains 6 black balls and 4 white balls. If two balls are selected at random without replacement, what is the probability that both balls are white?

prob of w * prob of w -1/1

If the average (arithmetic mean) of seven consecutive integers is k + 2, then the product of the greatest and least integer is

set of consecutive integers MEAN=MEDIAN

how to solve how many are above/ below quartile

take pop-1/2, -1 from that and divide in half, add whatever quartiles plus +1

we start w unlimited 20% solution and 50% solution and xL of first yL of second to get 7L of 40% . what does x equal?

we know x+y=7 and .2x+.5y=(7)(.4) solve for y in the first equat and plug in

If the average (arithmetic mean) of 24 consecutive odd integers is 48, what is the median of the 24 numbers?

when you have a sequence of numbers, (same number is added to each to get the next) the mean=the median