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Finding the Fourth Proportional to 1,289.70, 1,779.71 and 765.63

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Solution

The fourth proportional to 1,289.70, 1,779.71 and 765.63 is: 1,056.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.70 : 1,779.71 = 765.63 : x
  2. Step 2: Convert to fraction form
    1,289.70/1,779.71 = 765.63/x
  3. Step 3: Cross multiply
    1,289.70x = 1,779.71 × 765.63
  4. Step 4: Simplify right side
    1,289.70x = 1,362,595.54
  5. Step 5: Solve for x
    x = 1,362,595.54/1,289.70
  6. Step 6: Final answer
    x = 1,056.52

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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.