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Finding the Fourth Proportional to 385, 577.50 and 128.50

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Solution

The fourth proportional to 385, 577.50 and 128.50 is: 192.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    385 : 577.50 = 128.50 : x
  2. Step 2: Convert to fraction form
    385/577.50 = 128.50/x
  3. Step 3: Cross multiply
    385x = 577.50 × 128.50
  4. Step 4: Simplify right side
    385x = 74,208.75
  5. Step 5: Solve for x
    x = 74,208.75/385
  6. Step 6: Final answer
    x = 192.75

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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.