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Finding the Fourth Proportional to 782.40, 1,172.72 and 320.16

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Solution

The fourth proportional to 782.40, 1,172.72 and 320.16 is: 479.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.40 : 1,172.72 = 320.16 : x
  2. Step 2: Convert to fraction form
    782.40/1,172.72 = 320.16/x
  3. Step 3: Cross multiply
    782.40x = 1,172.72 × 320.16
  4. Step 4: Simplify right side
    782.40x = 375,458.04
  5. Step 5: Solve for x
    x = 375,458.04/782.40
  6. Step 6: Final answer
    x = 479.88

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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.