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Finding the Fourth Proportional to 921.68, 1,271.85 and 688.40

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Solution

The fourth proportional to 921.68, 1,271.85 and 688.40 is: 949.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.68 : 1,271.85 = 688.40 : x
  2. Step 2: Convert to fraction form
    921.68/1,271.85 = 688.40/x
  3. Step 3: Cross multiply
    921.68x = 1,271.85 × 688.40
  4. Step 4: Simplify right side
    921.68x = 875,535.18
  5. Step 5: Solve for x
    x = 875,535.18/921.68
  6. Step 6: Final answer
    x = 949.94

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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.