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Finding the Fourth Proportional to 102.36, 153.90 and 78.42

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Solution

The fourth proportional to 102.36, 153.90 and 78.42 is: 117.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.36 : 153.90 = 78.42 : x
  2. Step 2: Convert to fraction form
    102.36/153.90 = 78.42/x
  3. Step 3: Cross multiply
    102.36x = 153.90 × 78.42
  4. Step 4: Simplify right side
    102.36x = 12,068.84
  5. Step 5: Solve for x
    x = 12,068.84/102.36
  6. Step 6: Final answer
    x = 117.91

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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.