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Finding the Fourth Proportional to 412.50, 621.90 and 390

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Solution

The fourth proportional to 412.50, 621.90 and 390 is: 587.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    412.50 : 621.90 = 390 : x
  2. Step 2: Convert to fraction form
    412.50/621.90 = 390/x
  3. Step 3: Cross multiply
    412.50x = 621.90 × 390
  4. Step 4: Simplify right side
    412.50x = 242,541
  5. Step 5: Solve for x
    x = 242,541/412.50
  6. Step 6: Final answer
    x = 587.98

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.