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Finding the Fourth Proportional to 108.51, 162.90 and 78.09

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Solution

The fourth proportional to 108.51, 162.90 and 78.09 is: 117.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.51 : 162.90 = 78.09 : x
  2. Step 2: Convert to fraction form
    108.51/162.90 = 78.09/x
  3. Step 3: Cross multiply
    108.51x = 162.90 × 78.09
  4. Step 4: Simplify right side
    108.51x = 12,720.86
  5. Step 5: Solve for x
    x = 12,720.86/108.51
  6. Step 6: Final answer
    x = 117.23

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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.