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Finding the Fourth Proportional to 980.80, 1,355.40 and 947.92

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Solution

The fourth proportional to 980.80, 1,355.40 and 947.92 is: 1,309.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.80 : 1,355.40 = 947.92 : x
  2. Step 2: Convert to fraction form
    980.80/1,355.40 = 947.92/x
  3. Step 3: Cross multiply
    980.80x = 1,355.40 × 947.92
  4. Step 4: Simplify right side
    980.80x = 1,284,810.77
  5. Step 5: Solve for x
    x = 1,284,810.77/980.80
  6. Step 6: Final answer
    x = 1,309.96

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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.