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Finding the Fourth Proportional to 921.08, 1,271.18 and 687.80

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Solution

The fourth proportional to 921.08, 1,271.18 and 687.80 is: 949.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.08 : 1,271.18 = 687.80 : x
  2. Step 2: Convert to fraction form
    921.08/1,271.18 = 687.80/x
  3. Step 3: Cross multiply
    921.08x = 1,271.18 × 687.80
  4. Step 4: Simplify right side
    921.08x = 874,317.60
  5. Step 5: Solve for x
    x = 874,317.60/921.08
  6. Step 6: Final answer
    x = 949.23

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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.