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Finding the Fourth Proportional to 870.50, 1,305.75 and 485.75

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Solution

The fourth proportional to 870.50, 1,305.75 and 485.75 is: 728.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.50 : 1,305.75 = 485.75 : x
  2. Step 2: Convert to fraction form
    870.50/1,305.75 = 485.75/x
  3. Step 3: Cross multiply
    870.50x = 1,305.75 × 485.75
  4. Step 4: Simplify right side
    870.50x = 634,268.06
  5. Step 5: Solve for x
    x = 634,268.06/870.50
  6. Step 6: Final answer
    x = 728.63

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Double scale
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Similar ratio
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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.