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Finding the Fourth Proportional to 992.75, 1,369.80 and 638.78

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Solution

The fourth proportional to 992.75, 1,369.80 and 638.78 is: 881.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    992.75 : 1,369.80 = 638.78 : x
  2. Step 2: Convert to fraction form
    992.75/1,369.80 = 638.78/x
  3. Step 3: Cross multiply
    992.75x = 1,369.80 × 638.78
  4. Step 4: Simplify right side
    992.75x = 875,000.84
  5. Step 5: Solve for x
    x = 875,000.84/992.75
  6. Step 6: Final answer
    x = 881.39

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1.5x scale

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.