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Finding the Fourth Proportional to 78.25, 117.18 and 70.15

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Solution

The fourth proportional to 78.25, 117.18 and 70.15 is: 105.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.25 : 117.18 = 70.15 : x
  2. Step 2: Convert to fraction form
    78.25/117.18 = 70.15/x
  3. Step 3: Cross multiply
    78.25x = 117.18 × 70.15
  4. Step 4: Simplify right side
    78.25x = 8,220.18
  5. Step 5: Solve for x
    x = 8,220.18/78.25
  6. Step 6: Final answer
    x = 105.05

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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.