Home / 689.60-1,039.56-643.77

Finding the Fourth Proportional to 689.60, 1,039.56 and 643.77

Calculator

Solution

The fourth proportional to 689.60, 1,039.56 and 643.77 is: 970.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.60 : 1,039.56 = 643.77 : x
  2. Step 2: Convert to fraction form
    689.60/1,039.56 = 643.77/x
  3. Step 3: Cross multiply
    689.60x = 1,039.56 × 643.77
  4. Step 4: Simplify right side
    689.60x = 669,237.54
  5. Step 5: Solve for x
    x = 669,237.54/689.60
  6. Step 6: Final answer
    x = 970.48

Related Problems

Find fourth proportional to 344.80, 519.78 and 321.89
Half scale
Find fourth proportional to 1,379.19, 2,079.12 and 1,287.54
Double scale
Find fourth proportional to 690.60, 1,041.07 and 644.77
Similar ratio
Find fourth proportional to 1,034.39, 1,559.34 and 965.66
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.