Home / 209.90-289.65-121.38

Finding the Fourth Proportional to 209.90, 289.65 and 121.38

Calculator

Solution

The fourth proportional to 209.90, 289.65 and 121.38 is: 167.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.90 : 289.65 = 121.38 : x
  2. Step 2: Convert to fraction form
    209.90/289.65 = 121.38/x
  3. Step 3: Cross multiply
    209.90x = 289.65 × 121.38
  4. Step 4: Simplify right side
    209.90x = 35,157.72
  5. Step 5: Solve for x
    x = 35,157.72/209.90
  6. Step 6: Final answer
    x = 167.50

Related Problems

Find fourth proportional to 104.95, 144.83 and 60.69
Half scale
Find fourth proportional to 419.80, 579.30 and 242.76
Double scale
Find fourth proportional to 210.90, 291.03 and 122.38
Similar ratio
Find fourth proportional to 314.85, 434.48 and 182.07
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.