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Finding the Fourth Proportional to 920.90, 1,271.30 and 721.38

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Solution

The fourth proportional to 920.90, 1,271.30 and 721.38 is: 995.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.90 : 1,271.30 = 721.38 : x
  2. Step 2: Convert to fraction form
    920.90/1,271.30 = 721.38/x
  3. Step 3: Cross multiply
    920.90x = 1,271.30 × 721.38
  4. Step 4: Simplify right side
    920.90x = 917,090.39
  5. Step 5: Solve for x
    x = 917,090.39/920.90
  6. Step 6: Final answer
    x = 995.86

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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.