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Finding the Fourth Proportional to 810.96, 1,120.54 and 643.38

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Solution

The fourth proportional to 810.96, 1,120.54 and 643.38 is: 888.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.96 : 1,120.54 = 643.38 : x
  2. Step 2: Convert to fraction form
    810.96/1,120.54 = 643.38/x
  3. Step 3: Cross multiply
    810.96x = 1,120.54 × 643.38
  4. Step 4: Simplify right side
    810.96x = 720,933.03
  5. Step 5: Solve for x
    x = 720,933.03/810.96
  6. Step 6: Final answer
    x = 888.99

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Double scale
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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.