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Finding the Fourth Proportional to 78.21, 116.68 and 65.45

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Solution

The fourth proportional to 78.21, 116.68 and 65.45 is: 97.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.21 : 116.68 = 65.45 : x
  2. Step 2: Convert to fraction form
    78.21/116.68 = 65.45/x
  3. Step 3: Cross multiply
    78.21x = 116.68 × 65.45
  4. Step 4: Simplify right side
    78.21x = 7,636.38
  5. Step 5: Solve for x
    x = 7,636.38/78.21
  6. Step 6: Final answer
    x = 97.64

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.