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Finding the Fourth Proportional to 718.46, 991 and 663.78

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Solution

The fourth proportional to 718.46, 991 and 663.78 is: 915.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.46 : 991 = 663.78 : x
  2. Step 2: Convert to fraction form
    718.46/991 = 663.78/x
  3. Step 3: Cross multiply
    718.46x = 991 × 663.78
  4. Step 4: Simplify right side
    718.46x = 657,805.98
  5. Step 5: Solve for x
    x = 657,805.98/718.46
  6. Step 6: Final answer
    x = 915.58

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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.