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Finding the Fourth Proportional to 690.21, 1,035.42 and 319.86

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Solution

The fourth proportional to 690.21, 1,035.42 and 319.86 is: 479.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.21 : 1,035.42 = 319.86 : x
  2. Step 2: Convert to fraction form
    690.21/1,035.42 = 319.86/x
  3. Step 3: Cross multiply
    690.21x = 1,035.42 × 319.86
  4. Step 4: Simplify right side
    690.21x = 331,189.44
  5. Step 5: Solve for x
    x = 331,189.44/690.21
  6. Step 6: Final answer
    x = 479.84

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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.