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Finding the Fourth Proportional to 1,280.78, 1,919.78 and 621.26

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Solution

The fourth proportional to 1,280.78, 1,919.78 and 621.26 is: 931.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.78 : 1,919.78 = 621.26 : x
  2. Step 2: Convert to fraction form
    1,280.78/1,919.78 = 621.26/x
  3. Step 3: Cross multiply
    1,280.78x = 1,919.78 × 621.26
  4. Step 4: Simplify right side
    1,280.78x = 1,192,669.82
  5. Step 5: Solve for x
    x = 1,192,669.82/1,280.78
  6. Step 6: Final answer
    x = 931.21

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1.5x scale

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.