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Finding the Fourth Proportional to 1,309.61, 1,807.65 and 778.87

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Solution

The fourth proportional to 1,309.61, 1,807.65 and 778.87 is: 1,075.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,309.61 : 1,807.65 = 778.87 : x
  2. Step 2: Convert to fraction form
    1,309.61/1,807.65 = 778.87/x
  3. Step 3: Cross multiply
    1,309.61x = 1,807.65 × 778.87
  4. Step 4: Simplify right side
    1,309.61x = 1,407,919.34
  5. Step 5: Solve for x
    x = 1,407,919.34/1,309.61
  6. Step 6: Final answer
    x = 1,075.07

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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.