the cost of a telephone call is 5 pesos for the first three minutes and an additional of 2 pesos for each additional minute or fractional part thereof. find the cost of all call lasting: a) .5 min, b) 3 minutes, and c) 5 minutes

c(t)=5+2(t-3), t>3 

a) c(0.5)=5
b) c(3)=5
c) c(5)=5+2(5-3)=5+2(2)=9

if a bike has a 30% discount sale & is now $91 how much was the bike originally?

p - d = s 
p-0.3p=91 
0.7p=91 
p=91/0.7=130 
p=$130.00

how long will it take for a sum of money invested at 3% simple interest to double the original sum?

This will happen when I=P, so 
 
 

 

Joe invested $5,000 at 7.5% for 3 years. how much money did he have at the end of the 3 yeears?

the price of a used textbook after a 35% markdown is 29.25 what was the original price

$29.25 is after 35% so 

p-0.35p=29.25 


0.65p=29.25 


p=29.25/0.65=45 


:)

How much interest would I earn if I has deposited R20 000 in a bank account at 8.5% interest for a year

I=Prt 

P=20000
r=0.085
t=1 

I=$20000(0.085)(1)=$1,700 



:)

Internet Company A charges a $25 fee plus an additional $0.35 per hour. Internet Company B charges a $10 fee plus an additional $0.50 per hour. For what number of hours are the charges for both companies the same?

First we write their total charges as equations. Then we solve for t - the number of hours when both charges are equal 
 

 

When they charge the same A=B and we can write 

 

 

 



so t=100 hours 


:)

If you rent a car for 4 days, your bill will be $44. If you rent the same car for 10 days, your bill will be $100. Write an equation for the cost of the rental.

 

using the first situation of (4,44) 
 

 


:)

What annual rate of interest would you have to earn on an investment of 29000 dollars to ensure receiving 1450 dollars interest after one year?

Our working formula is the simple interest formula I=Prt with I=1450, P=29000,t=1 
1450=29000*r*1 
so r=1450/29000 = 0.05 
which is 5% 


:)

What is 12% of 45

12% of 45 means 


 

 
then we cancel to get 

27/5 which is 5 and 2/5 


:)

how much is $496 after taxes

"After taxes" differs from place to place, but the way we compute it does not, the values for this equation will depend on the tax rates:

After Taxes = 496 - 496r
where r is the tax rate

:)

After an 8% discount from the list price,the sale price of a key chain was $18.40. What was the list price of the key chain

Solution:

L-list price
S-sale price
D-discount 
D-8% of L so 
 

The sale price is how much it costs after the discount:

 

Now we substitute in the known values and solve for L:

 

so L=$20.00

If $1610 is invested in an account which earns 9% interest compounded monthly, which is the future value, to the nearest dollar, at the end of 14 years?

Solution:

The future value formula is:

and in our case P=$1610, r=0.09, n=12,t=14yrs so...

---

Mary is purchasing a new car and is researching loan rates at several banks. How much interest will Niles pay on his car loan if he finances $14,000 at an interest rate of 12.7% for 6 years?

Mary is purchasing a new car and is researching loan rates at several banks. How much interest will Niles pay on his car loan if he finances $14,000 at an interest rate of 12.7% for 6 years?

[A] $1167

[B] $11,128

[C] $1371

[D] $10,668

Solution:

This is a simple interest problem so 

where P=$14,000, r=0.127dollars per year, t=6yrs
and so

P=$10,668

---

The amount of a person’s paycheck, P, varies directly as the number of hours worked, t. For 13 hours of work, the pay is $88.40. Find the pay for 40 hours of work.

The amount of a person’s paycheck, P, varies directly as the number of hours worked, t. For 13 hours of work, the pay is $88.40. Find the pay for 40 hours of work.

[A] $272.00

[B] $282.00

[C] $278.80

[D] none of these