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Finding the Fourth Proportional to 1,289.28, 1,779.36 and 765.60

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Solution

The fourth proportional to 1,289.28, 1,779.36 and 765.60 is: 1,056.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.28 : 1,779.36 = 765.60 : x
  2. Step 2: Convert to fraction form
    1,289.28/1,779.36 = 765.60/x
  3. Step 3: Cross multiply
    1,289.28x = 1,779.36 × 765.60
  4. Step 4: Simplify right side
    1,289.28x = 1,362,278.02
  5. Step 5: Solve for x
    x = 1,362,278.02/1,289.28
  6. Step 6: Final answer
    x = 1,056.62

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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.