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Finding the Fourth Proportional to 921.58, 1,376.60 and 689.21

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Solution

The fourth proportional to 921.58, 1,376.60 and 689.21 is: 1,029.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.58 : 1,376.60 = 689.21 : x
  2. Step 2: Convert to fraction form
    921.58/1,376.60 = 689.21/x
  3. Step 3: Cross multiply
    921.58x = 1,376.60 × 689.21
  4. Step 4: Simplify right side
    921.58x = 948,761.32
  5. Step 5: Solve for x
    x = 948,761.32/921.58
  6. Step 6: Final answer
    x = 1,029.50

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.