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Finding the Fourth Proportional to 78.50, 117.78 and 40

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Solution

The fourth proportional to 78.50, 117.78 and 40 is: 60.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.50 : 117.78 = 40 : x
  2. Step 2: Convert to fraction form
    78.50/117.78 = 40/x
  3. Step 3: Cross multiply
    78.50x = 117.78 × 40
  4. Step 4: Simplify right side
    78.50x = 4,711.20
  5. Step 5: Solve for x
    x = 4,711.20/78.50
  6. Step 6: Final answer
    x = 60.02

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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.