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Finding the Fourth Proportional to 612.51, 845.40 and 391.78

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Solution

The fourth proportional to 612.51, 845.40 and 391.78 is: 540.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    612.51 : 845.40 = 391.78 : x
  2. Step 2: Convert to fraction form
    612.51/845.40 = 391.78/x
  3. Step 3: Cross multiply
    612.51x = 845.40 × 391.78
  4. Step 4: Simplify right side
    612.51x = 331,210.81
  5. Step 5: Solve for x
    x = 331,210.81/612.51
  6. Step 6: Final answer
    x = 540.74

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.