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Finding the Fourth Proportional to 690.54, 1,040.98 and 644.71

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Solution

The fourth proportional to 690.54, 1,040.98 and 644.71 is: 971.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.54 : 1,040.98 = 644.71 : x
  2. Step 2: Convert to fraction form
    690.54/1,040.98 = 644.71/x
  3. Step 3: Cross multiply
    690.54x = 1,040.98 × 644.71
  4. Step 4: Simplify right side
    690.54x = 671,122.59
  5. Step 5: Solve for x
    x = 671,122.59/690.54
  6. Step 6: Final answer
    x = 971.88

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.