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Finding the Fourth Proportional to 1,280.90, 1,921.35 and 916.40

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Solution

The fourth proportional to 1,280.90, 1,921.35 and 916.40 is: 1,374.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.90 : 1,921.35 = 916.40 : x
  2. Step 2: Convert to fraction form
    1,280.90/1,921.35 = 916.40/x
  3. Step 3: Cross multiply
    1,280.90x = 1,921.35 × 916.40
  4. Step 4: Simplify right side
    1,280.90x = 1,760,729.94
  5. Step 5: Solve for x
    x = 1,760,729.94/1,280.90
  6. Step 6: Final answer
    x = 1,374.60

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1.5x scale

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.