# Week 2 - Lesson 2 - Solving for P, r and t

## Re-arranging our basic simple interest formula to solve for principal, rate or time.

FinanceSimple Interest

# Week 2 - Lesson 2 - Solving for P, r and t

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Re-arranging our basic simple interest formula to solve for principal, rate or time.
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1. ### Slide 1 - Simple Interest – Lesson 2Solving for P, r and t

• Rob Sorensen
2. ### Slide 2 - More Simple Interest Formula

• We can re-arrange our basic formula to solve for P, r or t as follows:
• Rob Sorensen
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3. ### Slide 3 - Example – Finding the Principal

• How much would you have to deposit into a savings account paying 4% p.a. simple interest if you wanted to earn \$20.00 over 6 months?
• Rob Sorensen
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4. ### Slide 4 - Example – Finding the Rate

• If you borrow \$1,000 for 4 months and the lender charges you \$30 interest, what simple rate p.a. are they charging?
• Rob Sorensen
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5. ### Slide 5 - Example – Finding the Time

• How long will it take a \$5,000 investment to earn \$100 interest at a rate of 9% p.a.?
• Rob Sorensen
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6. ### Slide 6 - Rob Sorensen

• Try It Out!
• Joseph purchases an investment for \$90,000. He sold it 30 days later for \$91,000. What annual rate of return did he realize on his investment?
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