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Finding the Fourth Proportional to 1,399.68, 1,931.60 and 778.68

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Solution

The fourth proportional to 1,399.68, 1,931.60 and 778.68 is: 1,074.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,399.68 : 1,931.60 = 778.68 : x
  2. Step 2: Convert to fraction form
    1,399.68/1,931.60 = 778.68/x
  3. Step 3: Cross multiply
    1,399.68x = 1,931.60 × 778.68
  4. Step 4: Simplify right side
    1,399.68x = 1,504,098.29
  5. Step 5: Solve for x
    x = 1,504,098.29/1,399.68
  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.