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Finding the Fourth Proportional to 715.75, 987.84 and 421.18

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Solution

The fourth proportional to 715.75, 987.84 and 421.18 is: 581.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.75 : 987.84 = 421.18 : x
  2. Step 2: Convert to fraction form
    715.75/987.84 = 421.18/x
  3. Step 3: Cross multiply
    715.75x = 987.84 × 421.18
  4. Step 4: Simplify right side
    715.75x = 416,058.45
  5. Step 5: Solve for x
    x = 416,058.45/715.75
  6. Step 6: Final answer
    x = 581.29

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.