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Finding the Fourth Proportional to 856.42, 1,284.19 and 393.80

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Solution

The fourth proportional to 856.42, 1,284.19 and 393.80 is: 590.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.42 : 1,284.19 = 393.80 : x
  2. Step 2: Convert to fraction form
    856.42/1,284.19 = 393.80/x
  3. Step 3: Cross multiply
    856.42x = 1,284.19 × 393.80
  4. Step 4: Simplify right side
    856.42x = 505,714.02
  5. Step 5: Solve for x
    x = 505,714.02/856.42
  6. Step 6: Final answer
    x = 590.50

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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.