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Finding the Fourth Proportional to 921.21, 1,271.35 and 687.93

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Solution

The fourth proportional to 921.21, 1,271.35 and 687.93 is: 949.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.21 : 1,271.35 = 687.93 : x
  2. Step 2: Convert to fraction form
    921.21/1,271.35 = 687.93/x
  3. Step 3: Cross multiply
    921.21x = 1,271.35 × 687.93
  4. Step 4: Simplify right side
    921.21x = 874,595.17
  5. Step 5: Solve for x
    x = 874,595.17/921.21
  6. Step 6: Final answer
    x = 949.40

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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.