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Finding the Fourth Proportional to 921.58, 1,271.87 and 688.30

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Solution

The fourth proportional to 921.58, 1,271.87 and 688.30 is: 949.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.58 : 1,271.87 = 688.30 : x
  2. Step 2: Convert to fraction form
    921.58/1,271.87 = 688.30/x
  3. Step 3: Cross multiply
    921.58x = 1,271.87 × 688.30
  4. Step 4: Simplify right side
    921.58x = 875,428.12
  5. Step 5: Solve for x
    x = 875,428.12/921.58
  6. Step 6: Final answer
    x = 949.92

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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.