Home / 221.39-305.50-121.80

Finding the Fourth Proportional to 221.39, 305.50 and 121.80

Calculator

Solution

The fourth proportional to 221.39, 305.50 and 121.80 is: 168.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.39 : 305.50 = 121.80 : x
  2. Step 2: Convert to fraction form
    221.39/305.50 = 121.80/x
  3. Step 3: Cross multiply
    221.39x = 305.50 × 121.80
  4. Step 4: Simplify right side
    221.39x = 37,210.66
  5. Step 5: Solve for x
    x = 37,210.66/221.39
  6. Step 6: Final answer
    x = 168.08

Related Problems

Find fourth proportional to 110.70, 152.75 and 60.90
Half scale
Find fourth proportional to 442.79, 611 and 243.61
Double scale
Find fourth proportional to 222.39, 306.88 and 122.80
Similar ratio
Find fourth proportional to 332.09, 458.25 and 182.70
1.5x scale

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.