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Finding the Fourth Proportional to 921.42, 1,379.98 and 555.40

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Solution

The fourth proportional to 921.42, 1,379.98 and 555.40 is: 831.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.42 : 1,379.98 = 555.40 : x
  2. Step 2: Convert to fraction form
    921.42/1,379.98 = 555.40/x
  3. Step 3: Cross multiply
    921.42x = 1,379.98 × 555.40
  4. Step 4: Simplify right side
    921.42x = 766,440.89
  5. Step 5: Solve for x
    x = 766,440.89/921.42
  6. Step 6: Final answer
    x = 831.80

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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.