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Finding the Fourth Proportional to 1,309.74, 1,807.20 and 778.80

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Solution

The fourth proportional to 1,309.74, 1,807.20 and 778.80 is: 1,074.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,309.74 : 1,807.20 = 778.80 : x
  2. Step 2: Convert to fraction form
    1,309.74/1,807.20 = 778.80/x
  3. Step 3: Cross multiply
    1,309.74x = 1,807.20 × 778.80
  4. Step 4: Simplify right side
    1,309.74x = 1,407,447.36
  5. Step 5: Solve for x
    x = 1,407,447.36/1,309.74
  6. Step 6: Final answer
    x = 1,074.60

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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.