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Finding the Fourth Proportional to 764.40, 1,145.40 and 661.20

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Solution

The fourth proportional to 764.40, 1,145.40 and 661.20 is: 990.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    764.40 : 1,145.40 = 661.20 : x
  2. Step 2: Convert to fraction form
    764.40/1,145.40 = 661.20/x
  3. Step 3: Cross multiply
    764.40x = 1,145.40 × 661.20
  4. Step 4: Simplify right side
    764.40x = 757,338.48
  5. Step 5: Solve for x
    x = 757,338.48/764.40
  6. Step 6: Final answer
    x = 990.76

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.