Video Transcript
The pie chart shows the favourite
subjects of students in a class. Using the information given on the
pie chart, determine the percentage of students who chose English.
We know that the angles in a circle
or at a point sum to 360 degrees. In this case, our four angles 126
degrees, 95 degrees, 67 degrees, and 72 degrees add up to 360. In this question, we’re interested
in the students who chose English. This is represented by the blue
sector of the pie chart. As the English sector was equal to
72 degrees, we can say that 72 out of 360 degrees represents English.
We were asked to give our answer as
a percentage. And one way of converting from a
fraction to a percentage is by multiplying by 100. The word percent means out of
100. We could type this directly into
our calculator, which would give us an answer of 20.
Alternatively, we could do it in
two steps. We could firstly convert the
fraction into a decimal. 72 over 360 is the same as 72
divided by 360. This is equal to 0.2. We could then multiply 0.2 by 100
by moving all the digits two places to the left. Once again, this gives us an answer
of 20. 20 percent of the students in the
class said that their favourite subject was English.
An alternative method would’ve been
to simplify the fraction 72 out of 360. Remember, when simplifying a
fraction, whatever we do to the numerator we must do to the denominator. Both the numerator and denominator
are divisible by 36. Two times 36 is equal to 72. Therefore, 72 divided by 36 equals
two. 360 divided by 36 is equal to
10. Therefore, the fraction 72 out of
360 simplifies to two out of 10, or two-tenths.
We know that the fraction one-tenth
is equal to 10 percent. Therefore, two-tenths will be
double this. Once again, we have proved that the
fraction 72 out of 360 is equal to 20 percent. The fraction two-tenths could have
been simplified further to one-fifth. However, this is not required in
this case.
