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Finding the Fourth Proportional to 970.89, 1,338.79 and 721.80

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Solution

The fourth proportional to 970.89, 1,338.79 and 721.80 is: 995.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    970.89 : 1,338.79 = 721.80 : x
  2. Step 2: Convert to fraction form
    970.89/1,338.79 = 721.80/x
  3. Step 3: Cross multiply
    970.89x = 1,338.79 × 721.80
  4. Step 4: Simplify right side
    970.89x = 966,338.62
  5. Step 5: Solve for x
    x = 966,338.62/970.89
  6. Step 6: Final answer
    x = 995.31

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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.