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Finding the Fourth Proportional to 870.90, 1,307.70 and 665.70

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Solution

The fourth proportional to 870.90, 1,307.70 and 665.70 is: 999.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.90 : 1,307.70 = 665.70 : x
  2. Step 2: Convert to fraction form
    870.90/1,307.70 = 665.70/x
  3. Step 3: Cross multiply
    870.90x = 1,307.70 × 665.70
  4. Step 4: Simplify right side
    870.90x = 870,535.89
  5. Step 5: Solve for x
    x = 870,535.89/870.90
  6. Step 6: Final answer
    x = 999.58

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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.