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Section 3.4. Applications. Example 1. A coin bank holds nickels, dimes, and quarters. There are 45 coins in the bank and the value of the coins is $4.75. If there are five more nickels than quarters, find the number of each type of coin in the bank . N = # of nickels D = # of dimes
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Section 3.4 Applications
Example 1 • A coin bank holds nickels, dimes, and quarters. There are 45 coins in the bank and the value of the coins is $4.75. If there are five more nickels than quarters, find the number of each type of coin in the bank.
N = # of nickels • D = # of dimes • Q = # of quarters • We will use substitution to solve the 1st part of this problem.
Example 2 • John invested $6500 in three different mutual funds for one year. He earned a total of $560 in simple interest on the three investments. The first fund paid 5% interest, and the second fund paid 8% interest, and the third fund paid 10% interest. If the sum of the first two investments was $500 less than the amount of the third investment, find the amount he invested at each rate.
x = amount invested in 5% fund • y = amount invested in 8% fund • z = amount invested in 10% fund
Example 3 • The sum of the digits of a three digit number is 12. Five times the units digit plus 6 times the tens digit is 28. If 2 times the tens digit is subtracted from 3 times the hundreds digit, the result is 15. Find the number.
U = the units digit • T = the tens digit • H = the hundred digit