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Finding the Fourth Proportional to 208.50, 312.65 and 85.08

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Solution

The fourth proportional to 208.50, 312.65 and 85.08 is: 127.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.50 : 312.65 = 85.08 : x
  2. Step 2: Convert to fraction form
    208.50/312.65 = 85.08/x
  3. Step 3: Cross multiply
    208.50x = 312.65 × 85.08
  4. Step 4: Simplify right side
    208.50x = 26,599.84
  5. Step 5: Solve for x
    x = 26,599.84/208.50
  6. Step 6: Final answer
    x = 127.58

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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.