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Finding the Fourth Proportional to 679.40, 1,020.72 and 436.40

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Solution

The fourth proportional to 679.40, 1,020.72 and 436.40 is: 655.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.40 : 1,020.72 = 436.40 : x
  2. Step 2: Convert to fraction form
    679.40/1,020.72 = 436.40/x
  3. Step 3: Cross multiply
    679.40x = 1,020.72 × 436.40
  4. Step 4: Simplify right side
    679.40x = 445,442.21
  5. Step 5: Solve for x
    x = 445,442.21/679.40
  6. Step 6: Final answer
    x = 655.64

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.