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Finding the Fourth Proportional to 998.40, 1,378.56 and 689.28

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Solution

The fourth proportional to 998.40, 1,378.56 and 689.28 is: 951.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.40 : 1,378.56 = 689.28 : x
  2. Step 2: Convert to fraction form
    998.40/1,378.56 = 689.28/x
  3. Step 3: Cross multiply
    998.40x = 1,378.56 × 689.28
  4. Step 4: Simplify right side
    998.40x = 950,213.84
  5. Step 5: Solve for x
    x = 950,213.84/998.40
  6. Step 6: Final answer
    x = 951.74

Related Problems

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Double scale
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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.