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Finding the Fourth Proportional to 611.90, 918.15 and 287.21

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Solution

The fourth proportional to 611.90, 918.15 and 287.21 is: 430.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.90 : 918.15 = 287.21 : x
  2. Step 2: Convert to fraction form
    611.90/918.15 = 287.21/x
  3. Step 3: Cross multiply
    611.90x = 918.15 × 287.21
  4. Step 4: Simplify right side
    611.90x = 263,701.86
  5. Step 5: Solve for x
    x = 263,701.86/611.90
  6. Step 6: Final answer
    x = 430.96

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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.