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Finding the Fourth Proportional to 921.78, 1,271.88 and 528.80

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Solution

The fourth proportional to 921.78, 1,271.88 and 528.80 is: 729.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.78 : 1,271.88 = 528.80 : x
  2. Step 2: Convert to fraction form
    921.78/1,271.88 = 528.80/x
  3. Step 3: Cross multiply
    921.78x = 1,271.88 × 528.80
  4. Step 4: Simplify right side
    921.78x = 672,563.78
  5. Step 5: Solve for x
    x = 672,563.78/921.78
  6. Step 6: Final answer
    x = 729.64

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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.