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Finding the Fourth Proportional to 1,128.15, 1,690.75 and 780.93

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Solution

The fourth proportional to 1,128.15, 1,690.75 and 780.93 is: 1,170.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.15 : 1,690.75 = 780.93 : x
  2. Step 2: Convert to fraction form
    1,128.15/1,690.75 = 780.93/x
  3. Step 3: Cross multiply
    1,128.15x = 1,690.75 × 780.93
  4. Step 4: Simplify right side
    1,128.15x = 1,320,357.40
  5. Step 5: Solve for x
    x = 1,320,357.40/1,128.15
  6. Step 6: Final answer
    x = 1,170.37

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.