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Finding the Fourth Proportional to 1,200.15, 1,800.75 and 420.72

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Solution

The fourth proportional to 1,200.15, 1,800.75 and 420.72 is: 631.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,200.15 : 1,800.75 = 420.72 : x
  2. Step 2: Convert to fraction form
    1,200.15/1,800.75 = 420.72/x
  3. Step 3: Cross multiply
    1,200.15x = 1,800.75 × 420.72
  4. Step 4: Simplify right side
    1,200.15x = 757,602.54
  5. Step 5: Solve for x
    x = 757,602.54/1,200.15
  6. Step 6: Final answer
    x = 631.26

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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.