He should average 217.2 yards with 5 - iron
Solution:
Given that,
Ratio of the distance a 7-iron and a 5-iron will drive a golf ball 5 to 6
[tex]$\frac{\text { Distance using } 7 \text { iron }}{\text { Distance using } 5 \text { iron }}=\frac{5}{6}$[/tex]
The golfer averages 181 yards with a 7-iron
Let "x" be the average with 5 - iron
Therefore,
[tex]\frac{181}{x}=\frac{5}{6}[/tex]
Cross mulitply to get value of "x"
[tex]6 \times 181=5 \times x\\\\5x = 1086\\\\x = \frac{1086}{5}\\\\x = 217.2[/tex]
Thus he should average 217.2 yards with 5 - iron