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Finding the Fourth Proportional to 1,370, 1,890.72 and 780.32

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Solution

The fourth proportional to 1,370, 1,890.72 and 780.32 is: 1,076.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,370 : 1,890.72 = 780.32 : x
  2. Step 2: Convert to fraction form
    1,370/1,890.72 = 780.32/x
  3. Step 3: Cross multiply
    1,370x = 1,890.72 × 780.32
  4. Step 4: Simplify right side
    1,370x = 1,475,366.63
  5. Step 5: Solve for x
    x = 1,475,366.63/1,370
  6. Step 6: Final answer
    x = 1,076.91

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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.