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Finding the Fourth Proportional to 1,312.60, 1,969.80 and 947.70

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Solution

The fourth proportional to 1,312.60, 1,969.80 and 947.70 is: 1,422.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,312.60 : 1,969.80 = 947.70 : x
  2. Step 2: Convert to fraction form
    1,312.60/1,969.80 = 947.70/x
  3. Step 3: Cross multiply
    1,312.60x = 1,969.80 × 947.70
  4. Step 4: Simplify right side
    1,312.60x = 1,866,779.46
  5. Step 5: Solve for x
    x = 1,866,779.46/1,312.60
  6. Step 6: Final answer
    x = 1,422.20

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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.