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Finding the Fourth Proportional to 1,399.28, 1,931.04 and 778.28

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Solution

The fourth proportional to 1,399.28, 1,931.04 and 778.28 is: 1,074.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,399.28 : 1,931.04 = 778.28 : x
  2. Step 2: Convert to fraction form
    1,399.28/1,931.04 = 778.28/x
  3. Step 3: Cross multiply
    1,399.28x = 1,931.04 × 778.28
  4. Step 4: Simplify right side
    1,399.28x = 1,502,889.81
  5. Step 5: Solve for x
    x = 1,502,889.81/1,399.28
  6. Step 6: Final answer
    x = 1,074.05

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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.