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Finding the Fourth Proportional to 715.70, 1,070.55 and 643.10

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Solution

The fourth proportional to 715.70, 1,070.55 and 643.10 is: 961.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.70 : 1,070.55 = 643.10 : x
  2. Step 2: Convert to fraction form
    715.70/1,070.55 = 643.10/x
  3. Step 3: Cross multiply
    715.70x = 1,070.55 × 643.10
  4. Step 4: Simplify right side
    715.70x = 688,470.71
  5. Step 5: Solve for x
    x = 688,470.71/715.70
  6. Step 6: Final answer
    x = 961.95

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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.