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Finding the Fourth Proportional to 921.57, 1,271.54 and 642.39

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Solution

The fourth proportional to 921.57, 1,271.54 and 642.39 is: 886.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.57 : 1,271.54 = 642.39 : x
  2. Step 2: Convert to fraction form
    921.57/1,271.54 = 642.39/x
  3. Step 3: Cross multiply
    921.57x = 1,271.54 × 642.39
  4. Step 4: Simplify right side
    921.57x = 816,826.19
  5. Step 5: Solve for x
    x = 816,826.19/921.57
  6. Step 6: Final answer
    x = 886.34

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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.