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Finding the Fourth Proportional to 856.40, 1,281.90 and 672.80

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Solution

The fourth proportional to 856.40, 1,281.90 and 672.80 is: 1,007.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.40 : 1,281.90 = 672.80 : x
  2. Step 2: Convert to fraction form
    856.40/1,281.90 = 672.80/x
  3. Step 3: Cross multiply
    856.40x = 1,281.90 × 672.80
  4. Step 4: Simplify right side
    856.40x = 862,462.32
  5. Step 5: Solve for x
    x = 862,462.32/856.40
  6. Step 6: Final answer
    x = 1,007.08

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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.