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Finding the Fourth Proportional to 689.41, 1,028.80 and 615.50

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Solution

The fourth proportional to 689.41, 1,028.80 and 615.50 is: 918.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.41 : 1,028.80 = 615.50 : x
  2. Step 2: Convert to fraction form
    689.41/1,028.80 = 615.50/x
  3. Step 3: Cross multiply
    689.41x = 1,028.80 × 615.50
  4. Step 4: Simplify right side
    689.41x = 633,225.88
  5. Step 5: Solve for x
    x = 633,225.88/689.41
  6. Step 6: Final answer
    x = 918.50

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.