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Finding the Fourth Proportional to 78, 117.14 and 64.50

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Solution

The fourth proportional to 78, 117.14 and 64.50 is: 96.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    78 : 117.14 = 64.50 : x
  2. Step 2: Convert to fraction form
    78/117.14 = 64.50/x
  3. Step 3: Cross multiply
    78x = 117.14 × 64.50
  4. Step 4: Simplify right side
    78x = 7,555.53
  5. Step 5: Solve for x
    x = 7,555.53/78
  6. Step 6: Final answer
    x = 96.87

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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.