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Finding the Fourth Proportional to 72.90, 100.60 and 40.15

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Solution

The fourth proportional to 72.90, 100.60 and 40.15 is: 55.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.90 : 100.60 = 40.15 : x
  2. Step 2: Convert to fraction form
    72.90/100.60 = 40.15/x
  3. Step 3: Cross multiply
    72.90x = 100.60 × 40.15
  4. Step 4: Simplify right side
    72.90x = 4,038.83
  5. Step 5: Solve for x
    x = 4,038.83/72.90
  6. Step 6: Final answer
    x = 55.40

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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.