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Finding the Fourth Proportional to 912.80, 1,258.80 and 765.20

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Solution

The fourth proportional to 912.80, 1,258.80 and 765.20 is: 1,055.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    912.80 : 1,258.80 = 765.20 : x
  2. Step 2: Convert to fraction form
    912.80/1,258.80 = 765.20/x
  3. Step 3: Cross multiply
    912.80x = 1,258.80 × 765.20
  4. Step 4: Simplify right side
    912.80x = 963,233.76
  5. Step 5: Solve for x
    x = 963,233.76/912.80
  6. Step 6: Final answer
    x = 1,055.25

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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.