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Finding the Fourth Proportional to 921.63, 1,271.79 and 528.78

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Solution

The fourth proportional to 921.63, 1,271.79 and 528.78 is: 729.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.63 : 1,271.79 = 528.78 : x
  2. Step 2: Convert to fraction form
    921.63/1,271.79 = 528.78/x
  3. Step 3: Cross multiply
    921.63x = 1,271.79 × 528.78
  4. Step 4: Simplify right side
    921.63x = 672,497.12
  5. Step 5: Solve for x
    x = 672,497.12/921.63
  6. Step 6: Final answer
    x = 729.68

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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.