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Finding the Fourth Proportional to 1,390.70, 1,918.86 and 801.20

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Solution

The fourth proportional to 1,390.70, 1,918.86 and 801.20 is: 1,105.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.70 : 1,918.86 = 801.20 : x
  2. Step 2: Convert to fraction form
    1,390.70/1,918.86 = 801.20/x
  3. Step 3: Cross multiply
    1,390.70x = 1,918.86 × 801.20
  4. Step 4: Simplify right side
    1,390.70x = 1,537,390.63
  5. Step 5: Solve for x
    x = 1,537,390.63/1,390.70
  6. Step 6: Final answer
    x = 1,105.48

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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.