Math 2/ percents Flashcards
average rate
be careful!! this is not RX T=D
average rate for a journey is the total distance divided by the total time!!!
you cannot take the average of the rates for the two parts of the trip.
YOU NEED TOTAL DISTANCE/TOTAL TIME
ex. for average rate
Gus takes 2 hours to bike 12 kilometers from home to school. If Gul bikes back home by the same route at a rate of 4 kilometers per hour, what is the average rate, in kilometers per hour, for the entire trip?
average kms per hour= total kilometers/total hours
route frm home to school= 12 km
Gul goes by the same route so total kilometers traveled is 12+12= 24
a=average kms per hour= total distance/total time
a= 24/total hours
total hours= horus spent in first part of trip and hours in second part of the trip
RXT=D, 4XT= 12, T=3
so total time 2+3 = 5 hours
now a= 24/5, average rate/speed for entire trip= 4.8 km pr hour
WORK PROBLEMS
Jay can build a chair in 3 hours. Kay can build a char in 5 hours. How long will it take both of them, working together, to build 8 chairs?
a. Jay’s rate = 1 chair/3 hours= 1/3 chairs per hour
in 1 hour jay can build 1/3 of a chair
b. Kay’s rate= 1 chair/5 hours= 1/5 chair per hour
together the can build 1/3 + 1/5 of a chair in an hour
c. FIND SUM OF RATES ALWAYS
1/3+1/5=1/….
1/3 +1/5= 8/15 chair per hour
J and Kay can build a chair in 1 hour. similar to 1.5
RX T= Work
work takes place of distance
so 8/15 x T= 8 chairs
T= 8 x (15/8)
T=15 hours
m is twice p
m=2p
one fifth of y
(1/5)y
A is 4 times the length of B
A=4B
total revenue=
total revenue= Price X quantity
never forget
Profit=Revenues-Costs
total cost to consumer=
total cost to consumer= Price X quantity
Never forget:
Profit=Revenues-Costs
For fixed cost
if you have a fixed cost for cell phone for call per minute then you paid for additional min at a certain price
equation
Total cost= Fixed cost + Price X Additional quantity
a technician takes 3 hours to complete the job:
Rate= 1job/ 3 hours = 1/3 job per hour
Norman is 12 years older than Mica. In 6 years, he will be twice as old as Mica. how old is Norman?
N=M+12
in 6 yrs N+6= 2(M+6)
solve
4 kids collect 33 candies that fall out of pinata. If 3 of the children pick up the same number of candies and the fourth child picks up 3 fewer candies than each of the other children, how many candies does the 4th child collect?
let c stand for each of the 3 children who picked up the same amount of candies. Let f stand for the 4th kid. therefore:
Eq 1. c+c+c+f=33
e1. 2= f=c-3
plug in 3c+f=33, 3c +(c-3)= 33
c=9 so f must be 6
Fixed cost Q
Arnaldo earns $11 for each ticket he sells plus a bonus of $2 per ticket for each ticket he sells over the first 100 tickets. If Arnaldo was paid $2,400. How many tickets did he sell?
11x+2(x-100)=2,400
11x+2x-200=2,400
13x=2,600
x=200
Ch9 work=rate x time Q
Machine A produces 15 widgets per minute. Machine B produces 18 widgets per minute. How many widgets will the machines produce together in 20 minutes?
since the two machines are working together, add their rates!
15+18=33 widgets per minute
In 10 minutes, they produce 330 widgets. In 20 minutes, they produce twice that or 660 widgets per minute
* W=RXT* ADD RATES
1/100
.01
1%
1/20
0.05
5%
1/10
.1
10%
1/8
0.125
12.5%
1/5
0.2
20%
1/4
0.25
25%
1/3
0.3333
33.33%
3/10
0.3
30%
3/8
0.375
37.5%
2/5
40%
0.40
