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Finding the Fourth Proportional to 66.28, 90.65 and 65.21

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Solution

The fourth proportional to 66.28, 90.65 and 65.21 is: 89.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.28 : 90.65 = 65.21 : x
  2. Step 2: Convert to fraction form
    66.28/90.65 = 65.21/x
  3. Step 3: Cross multiply
    66.28x = 90.65 × 65.21
  4. Step 4: Simplify right side
    66.28x = 5,911.29
  5. Step 5: Solve for x
    x = 5,911.29/66.28
  6. Step 6: Final answer
    x = 89.19

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.