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Finding the Fourth Proportional to 856.72, 1,285.20 and 279.64

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Solution

The fourth proportional to 856.72, 1,285.20 and 279.64 is: 419.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.72 : 1,285.20 = 279.64 : x
  2. Step 2: Convert to fraction form
    856.72/1,285.20 = 279.64/x
  3. Step 3: Cross multiply
    856.72x = 1,285.20 × 279.64
  4. Step 4: Simplify right side
    856.72x = 359,393.33
  5. Step 5: Solve for x
    x = 359,393.33/856.72
  6. Step 6: Final answer
    x = 419.50

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1.5x scale

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.