Answer
Required proportion : $\frac{2 left-handed-students}{15 total-students} = \frac{x left-handed-students}{650 total-students}$
Solution : $x \approx 87$, i.e. 87 students can be expected left handed out of 650 students.
Work Step by Step
About 2 out of every 15 people are left-handed. How many of the 650 students in our school would you expect to be left-handed? Round to the nearest whole number.
As per the details given: $\frac{2 left-handed-students}{15 total-students} = \frac{x left-handed-students}{650 total-students}$ (Assumed x as a required no of left handed students)
i.e. $2 \times650 = 15 \times x$ (As bot sides have same numerator and denominator)
Now, divide both sides by 15,
$1300 \div 15 = 15 x \div 15$
$ x = 86.7 \approx 87$