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Finding the Fourth Proportional to 715.99, 987.78 and 421.15

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Solution

The fourth proportional to 715.99, 987.78 and 421.15 is: 581.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.99 : 987.78 = 421.15 : x
  2. Step 2: Convert to fraction form
    715.99/987.78 = 421.15/x
  3. Step 3: Cross multiply
    715.99x = 987.78 × 421.15
  4. Step 4: Simplify right side
    715.99x = 416,003.55
  5. Step 5: Solve for x
    x = 416,003.55/715.99
  6. Step 6: Final answer
    x = 581.02

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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.