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Finding the Fourth Proportional to 778.40, 1,091.20 and 778.40

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Solution

The fourth proportional to 778.40, 1,091.20 and 778.40 is: 1,091.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    778.40 : 1,091.20 = 778.40 : x
  2. Step 2: Convert to fraction form
    778.40/1,091.20 = 778.40/x
  3. Step 3: Cross multiply
    778.40x = 1,091.20 × 778.40
  4. Step 4: Simplify right side
    778.40x = 849,390.08
  5. Step 5: Solve for x
    x = 849,390.08/778.40
  6. Step 6: Final answer
    x = 1,091.20

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.