WEBVTT
00:00:02.720 --> 00:00:06.440
The ratio of green pens to black pens in a box is two to seven.
00:00:07.320 --> 00:00:09.720
What fraction of the total number of pens are green?
00:00:10.400 --> 00:00:11.400
Circle your answer.
00:00:12.200 --> 00:00:18.160
The options are half, two-sevenths, two-ninths, and seven-ninths.
00:00:19.880 --> 00:00:23.680
The first thing we need to do when we’re looking at a ratio is look at the order.
00:00:24.720 --> 00:00:29.640
We’re told that the ratio of green pens to black pens in a box is two to seven.
00:00:31.400 --> 00:00:36.640
So therefore, as green comes first, that’s gonna correspond to the two, so two parts.
00:00:37.320 --> 00:00:38.200
And then we have black.
00:00:38.520 --> 00:00:41.480
So that’s gonna correspond to seven, so seven parts.
00:00:43.080 --> 00:00:49.680
So then what we know is that there are two parts which are green pens, seven parts which are black pens.
00:00:49.680 --> 00:00:52.280
And what we want to know is what are the total number of parts.
00:00:53.000 --> 00:00:58.480
So to find this out, we add two and seven, which is going to be nine.
00:00:58.840 --> 00:01:01.000
So we know that there are nine parts in total.
00:01:03.000 --> 00:01:08.200
So now what we want to do is find out the fraction of the total number of pens that are green.
00:01:08.200 --> 00:01:12.800
Well, we know that the total number of parts is nine.
00:01:14.760 --> 00:01:17.440
And two of those nine parts are green.
00:01:19.360 --> 00:01:26.560
So therefore, we can say that green is equal to two-ninths of the total number of pens.
00:01:27.200 --> 00:01:29.840
And we get that because two parts are green.
00:01:30.240 --> 00:01:31.200
And that’s our numerator.
00:01:31.760 --> 00:01:34.440
And then our denominator is the total parts, which is nine.
00:01:36.520 --> 00:01:45.800
So we can circle the correct answer, which is the third answer, two-ninths, because two-ninths is the fraction of total number of pens that are green.