SOLUTION: Can someone help me with these questions please? A principal of $5000 was invested in a savings account for 4 years. If the interest earned for the period was $400, what was th

Algebra ->  Expressions-with-variables -> SOLUTION: Can someone help me with these questions please? A principal of $5000 was invested in a savings account for 4 years. If the interest earned for the period was $400, what was th      Log On


   

Question 37589: Can someone help me with these questions please?
A principal of $5000 was invested in a savings account for 4 years. If the interest earned for the period was $400, what was the interest rate?
Allen bought 20 stamps at the post office in 37¢ and 20¢ denominations. If the total cost of the stamps was $7.06, how many 37¢ stamps did Allen buy?
The perimeter of a rectangle is to be no greater than 300 in., and the length must be 125 in. Find the maximum width of the rectangle.
One number is 8 less than another. If 5 times the smaller number minus 2 times the larger number is 14, find the two numbers.
Answer by Nate(3500) About Me  (Show Source):
You can put this solution on YOUR website!
A principal of $5000 was invested in a savings account for 4 years. If the interest earned for the period was $400, what was the interest rate?
P%28a%29=a%281%2Br%29%5Et your equation for interest
5400=5000%281%2Br%29%5E4 where P%28a%29 is final amount; a is initial amount; r is rate; and t is time
%281.08%29=%281%2Br%29%5E4
1.0194=1%2Br
0.0194=r the rate was about 1.94%
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Allen bought 20 stamps at the post office in 37¢ and 20¢ denominations. If the total cost of the stamps was $7.06, how many 37¢ stamps did Allen buy?
define variables:
s=amount of 20¢
l=amount of 37¢
define equations:
s+l=20
0.2s+.37l=7.06
combine:
s=20-l
so....
0.2(20-l)+.37l=7.06
4-.2l+.37l=7.06
.17l=3.06
l=18 Allen bought eighteen 37¢ stamps.
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The perimeter of a rectangle is to be no greater than 300 in., and the length must be 125 in. Find the maximum width of the rectangle.
perimeter<2(length)+2(width)
300>2(125)+2(w)
300>250+2w
50>2w
25>w the maximum width must be less than twenty five .... (if you only concidered integer values, than the value would be 24)
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One number is 8 less than another. If 5 times the smaller number minus 2 times the larger number is 14, find the two numbers.
define variables:
l=larger number
s=smaller number
create equations:
l-8=s
5s-2l=14
combine:
s=l-8
so ....
5s-2l=14
5(l-8)+2l=14
5l-40+2l=14
3l=54
l=18
s=10