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Finding the Fourth Proportional to 856.40, 1,281.90 and 613.40

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Solution

The fourth proportional to 856.40, 1,281.90 and 613.40 is: 918.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.40 : 1,281.90 = 613.40 : x
  2. Step 2: Convert to fraction form
    856.40/1,281.90 = 613.40/x
  3. Step 3: Cross multiply
    856.40x = 1,281.90 × 613.40
  4. Step 4: Simplify right side
    856.40x = 786,317.46
  5. Step 5: Solve for x
    x = 786,317.46/856.40
  6. Step 6: Final answer
    x = 918.17

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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.