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Finding the Fourth Proportional to 258.58, 387.88 and 66.21

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Solution

The fourth proportional to 258.58, 387.88 and 66.21 is: 99.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.58 : 387.88 = 66.21 : x
  2. Step 2: Convert to fraction form
    258.58/387.88 = 66.21/x
  3. Step 3: Cross multiply
    258.58x = 387.88 × 66.21
  4. Step 4: Simplify right side
    258.58x = 25,681.53
  5. Step 5: Solve for x
    x = 25,681.53/258.58
  6. Step 6: Final answer
    x = 99.32

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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.