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Finding the Fourth Proportional to 124.78, 172.21 and 74.99

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Solution

The fourth proportional to 124.78, 172.21 and 74.99 is: 103.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.78 : 172.21 = 74.99 : x
  2. Step 2: Convert to fraction form
    124.78/172.21 = 74.99/x
  3. Step 3: Cross multiply
    124.78x = 172.21 × 74.99
  4. Step 4: Simplify right side
    124.78x = 12,914.41
  5. Step 5: Solve for x
    x = 12,914.41/124.78
  6. Step 6: Final answer
    x = 103.50

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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.