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Finding the Fourth Proportional to 715.20, 1,072.80 and 666.60

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Solution

The fourth proportional to 715.20, 1,072.80 and 666.60 is: 999.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.20 : 1,072.80 = 666.60 : x
  2. Step 2: Convert to fraction form
    715.20/1,072.80 = 666.60/x
  3. Step 3: Cross multiply
    715.20x = 1,072.80 × 666.60
  4. Step 4: Simplify right side
    715.20x = 715,128.48
  5. Step 5: Solve for x
    x = 715,128.48/715.20
  6. Step 6: Final answer
    x = 999.90

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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.