Home / 819.60-1,229.40-429.45

Finding the Fourth Proportional to 819.60, 1,229.40 and 429.45

Calculator

Solution

The fourth proportional to 819.60, 1,229.40 and 429.45 is: 644.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.60 : 1,229.40 = 429.45 : x
  2. Step 2: Convert to fraction form
    819.60/1,229.40 = 429.45/x
  3. Step 3: Cross multiply
    819.60x = 1,229.40 × 429.45
  4. Step 4: Simplify right side
    819.60x = 527,965.83
  5. Step 5: Solve for x
    x = 527,965.83/819.60
  6. Step 6: Final answer
    x = 644.18

Related Problems

Find fourth proportional to 409.80, 614.70 and 214.73
Half scale
Find fourth proportional to 1,639.20, 2,458.80 and 858.90
Double scale
Find fourth proportional to 820.60, 1,230.90 and 430.45
Similar ratio
Find fourth proportional to 1,229.40, 1,844.10 and 644.18
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.