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Finding the Fourth Proportional to 1,010.40, 1,398.96 and 991.20

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Solution

The fourth proportional to 1,010.40, 1,398.96 and 991.20 is: 1,372.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,010.40 : 1,398.96 = 991.20 : x
  2. Step 2: Convert to fraction form
    1,010.40/1,398.96 = 991.20/x
  3. Step 3: Cross multiply
    1,010.40x = 1,398.96 × 991.20
  4. Step 4: Simplify right side
    1,010.40x = 1,386,649.15
  5. Step 5: Solve for x
    x = 1,386,649.15/1,010.40
  6. Step 6: Final answer
    x = 1,372.38

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1.5x scale

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.