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Finding the Fourth Proportional to 1,078.80, 1,488.90 and 686.40

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Solution

The fourth proportional to 1,078.80, 1,488.90 and 686.40 is: 947.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,078.80 : 1,488.90 = 686.40 : x
  2. Step 2: Convert to fraction form
    1,078.80/1,488.90 = 686.40/x
  3. Step 3: Cross multiply
    1,078.80x = 1,488.90 × 686.40
  4. Step 4: Simplify right side
    1,078.80x = 1,021,980.96
  5. Step 5: Solve for x
    x = 1,021,980.96/1,078.80
  6. Step 6: Final answer
    x = 947.33

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1.5x scale

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.