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Finding the Fourth Proportional to 1,288.40, 1,778.08 and 728.89

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Solution

The fourth proportional to 1,288.40, 1,778.08 and 728.89 is: 1,005.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.40 : 1,778.08 = 728.89 : x
  2. Step 2: Convert to fraction form
    1,288.40/1,778.08 = 728.89/x
  3. Step 3: Cross multiply
    1,288.40x = 1,778.08 × 728.89
  4. Step 4: Simplify right side
    1,288.40x = 1,296,018.46
  5. Step 5: Solve for x
    x = 1,296,018.46/1,288.40
  6. Step 6: Final answer
    x = 1,005.92

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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.