Video Transcript
Between 2006 and 2007, smartphone
users increased from 7.7 million to 31 million. Determine to the nearest whole
percent the percentage increase.
Well, the key information here is
that we start off from 7.7 million and we increase to 31 million. Now they’re both in millions. So that’s handy. Right! The percentage increase is the
amount of the increase divided by the original amount. So that’s the proportion of the
original amount that the increase represents. And then we multiply that by 100 to
turn it into a percentage.
Now remember we went from 7.7 to
31. So to calculate the amount of
increase, we need to do 31 take away 7.7. And 31 take away 7.7 I’ve written
it down. I’m gonna write 31 as 31.0 to make
it easier to do this as a column calculation. And so we’re gonna do zero take
away seven. But we can’t do that. So we’re gonna have to do some
borrowing.
We’ll borrow one from the next
column along and use it here. So 10 take away seven is three. And then we’ve got the same
problem, zero take away seven. So I’m gonna have to borrow one
from the next column and use it in this column. So again, we’ve got 10 take away
seven, which is three. And then we’ve got two take away
nothing, which is two. So the difference was 23.3. That was an increase of 23.3
million.
Now just as an aside, another way
of approaching that calculation would have been to draw it on a number line like
this. So let’s go to the next whole
number. So from 7.7 to eight would be an
increase of 0.3. And then from eight to 31 would be
an increase of 23. So 0.3 plus 23 equals 23.3. Some people find that method easier
rather than all this borrowing business.
Okay, so now we’ve got some figures
that we can fill in for our percentage increase. The amount of the increase was
23.3. And the original amount was
7.7. And then we’re going to multiply
that by 100. Now I’m just gonna enter that into
the calculator rather than to go into all of the long division process. And that gives me 302.5974026, and
so on.
Well, the question asked us to give
our answer to the nearest whole percent. So I’m going to have to round here,
so 302. Well it’s .5. Well if it’s five or above, we’re
gonna round up. So that’s gonna be 303. So the answer is that we had a 303
percent increase to the nearest whole percent.
