Home / 807.60-1,211.40-422.80

Finding the Fourth Proportional to 807.60, 1,211.40 and 422.80

Calculator

Solution

The fourth proportional to 807.60, 1,211.40 and 422.80 is: 634.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    807.60 : 1,211.40 = 422.80 : x
  2. Step 2: Convert to fraction form
    807.60/1,211.40 = 422.80/x
  3. Step 3: Cross multiply
    807.60x = 1,211.40 × 422.80
  4. Step 4: Simplify right side
    807.60x = 512,179.92
  5. Step 5: Solve for x
    x = 512,179.92/807.60
  6. Step 6: Final answer
    x = 634.20

Related Problems

Find fourth proportional to 403.80, 605.70 and 211.40
Half scale
Find fourth proportional to 1,615.20, 2,422.80 and 845.60
Double scale
Find fourth proportional to 808.60, 1,212.90 and 423.80
Similar ratio
Find fourth proportional to 1,211.40, 1,817.10 and 634.20
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.