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Finding the Fourth Proportional to 781.60, 1,172.40 and 456.80

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Solution

The fourth proportional to 781.60, 1,172.40 and 456.80 is: 685.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.60 : 1,172.40 = 456.80 : x
  2. Step 2: Convert to fraction form
    781.60/1,172.40 = 456.80/x
  3. Step 3: Cross multiply
    781.60x = 1,172.40 × 456.80
  4. Step 4: Simplify right side
    781.60x = 535,552.32
  5. Step 5: Solve for x
    x = 535,552.32/781.60
  6. Step 6: Final answer
    x = 685.20

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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.