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Finding the Fourth Proportional to 668.80, 1,004.40 and 647.20

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Solution

The fourth proportional to 668.80, 1,004.40 and 647.20 is: 971.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    668.80 : 1,004.40 = 647.20 : x
  2. Step 2: Convert to fraction form
    668.80/1,004.40 = 647.20/x
  3. Step 3: Cross multiply
    668.80x = 1,004.40 × 647.20
  4. Step 4: Simplify right side
    668.80x = 650,047.68
  5. Step 5: Solve for x
    x = 650,047.68/668.80
  6. Step 6: Final answer
    x = 971.96

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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.