Home / 261.39-392.09-78.80

Finding the Fourth Proportional to 261.39, 392.09 and 78.80

Calculator

Solution

The fourth proportional to 261.39, 392.09 and 78.80 is: 118.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.39 : 392.09 = 78.80 : x
  2. Step 2: Convert to fraction form
    261.39/392.09 = 78.80/x
  3. Step 3: Cross multiply
    261.39x = 392.09 × 78.80
  4. Step 4: Simplify right side
    261.39x = 30,894.34
  5. Step 5: Solve for x
    x = 30,894.34/261.39
  6. Step 6: Final answer
    x = 118.19

Related Problems

Find fourth proportional to 130.70, 196.04 and 39.40
Half scale
Find fourth proportional to 522.78, 784.17 and 157.59
Double scale
Find fourth proportional to 262.39, 393.59 and 79.80
Similar ratio
Find fourth proportional to 392.09, 588.13 and 118.19
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.