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Finding the Fourth Proportional to 861.64, 1,290.30 and 655.90

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Solution

The fourth proportional to 861.64, 1,290.30 and 655.90 is: 982.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.64 : 1,290.30 = 655.90 : x
  2. Step 2: Convert to fraction form
    861.64/1,290.30 = 655.90/x
  3. Step 3: Cross multiply
    861.64x = 1,290.30 × 655.90
  4. Step 4: Simplify right side
    861.64x = 846,307.77
  5. Step 5: Solve for x
    x = 846,307.77/861.64
  6. Step 6: Final answer
    x = 982.21

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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.