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Finding the Fourth Proportional to 782.40, 1,172.80 and 392.16

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Solution

The fourth proportional to 782.40, 1,172.80 and 392.16 is: 587.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    782.40 : 1,172.80 = 392.16 : x
  2. Step 2: Convert to fraction form
    782.40/1,172.80 = 392.16/x
  3. Step 3: Cross multiply
    782.40x = 1,172.80 × 392.16
  4. Step 4: Simplify right side
    782.40x = 459,925.25
  5. Step 5: Solve for x
    x = 459,925.25/782.40
  6. Step 6: Final answer
    x = 587.84

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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.