What Do I Need To Get An A In This Class?


After writing my bit about how to figure out what grade you need to pass your class, I thought some more and realized that while everything in it is true, it’s not necessarily helpful, because people get panicky at formulas. So I thought to make up some tables showing what you need, if you go in with a certain grade, to pass, or get a B, or an A, or what not, for different weightings of the final exam. That’s easy enough to do especially once I set up a Matlab (well, an Octave) script to build the tables for me.

In these tables, the row is your current score, and I should clarify that’s your percentage score. This doesn’t have anything directly to do with the number of points you might have got on different assignments because not all points carry the same weight: ten points on your midterm (probably) counts for more than ten points on homework number three out of twelve assignments. And, obviously, I’m not listing all the possible percentage scores you might have going into the final because that produces a table that’s boringly long. The column is what score you want to get, and I picked 60, 65, 70, 80, and 90 as the most likely useful targets.

The tables were easiest to read by making a new table for each of the different weightings I considered. So there’s one table for final exams worth 1/3rd of the class grade, one for finals worth 30 percent, for finals worth 25 percent, and for finals worth 20 percent. None of these consider any extra credit you might have gotten, or extra penalties drawn because you couldn’t put the cell phone down for 75 minutes of class, but this will at least let you get close to knowing how well you have to do. The final’s weight could be anything, I admit, but these seemed like the most likely values to come up; if there’s a lot of demand to work this out for, say, a final worth 40 percent of the course let me know and I’ll add that in.

To use the tables, go to the table for your class’s weighting, then look to the row with whatever’s the best fit for your pre-final percentage, and then across to the column matching what score you need.

For example, if your final is one-third the course average, and you’ve got an 84 going in, and you want a 90 in the course, then, that’s the first table, and the fourth row (matching a percentage of 85), and the last column in that: aim to get at least 100 … well, that’s a long shot, but you are trying to go from an 84 up to a 90 with one exam. If the final is 20 percent of the course grade, and going in to the final you have 66 percent, and you want to get at least a C, 70 percent, then that’s going to the last of these tables, and to the row starting 65, and across three columns: you need about a 90. Good luck.

And, yes, if you’re going in with a great score and just want to pass you can be in a quite comfortable position. Suppose the final is 25 percent of the course grade, you’re going in with 89 percent, and all you want to do is pass. The 25-percent table shows that you need a score of about -30 on the exam so you could just sleep in and skip the whole business, but your instructor will be quite disappointed in you if you do.

Final Worth 40 Percent (2/5) Of The Course Score:

To Get
60 65 70 80 90
If You Have Requires
100 0 12 25 50 75
95 7 20 32 57 82
90 15 27 40 65 90
85 22 35 47 72 97
80 30 42 55 80 105
75 37 50 62 87 112
70 45 57 70 95 120
65 52 65 77 102 127
60 60 72 85 110 135
55 67 80 92 117 142
50 75 87 100 125 150
45 82 95 107 132 157
40 90 102 115 140 165
35 97 110 122 147 172
30 105 117 130 155 180

Final Worth 1/3 Of The Course Score:

To Get
60 65 70 80 90
If You Have Requires
100 -20 -5 10 40 70
95 -10 5 20 50 80
90 0 15 30 60 90
85 10 25 40 70 100
80 20 35 50 80 110
75 30 45 60 90 120
70 40 55 70 100 130
65 50 65 80 110 140
60 60 75 90 120 150
55 70 85 100 130 160
50 80 95 110 140 170
45 90 105 120 150 180
40 100 115 130 160 190
35 110 125 140 170 200

Final Worth 30 Percent (3/10) Of The Course Score:

To Get
60 65 70 80 90
If You Have Requires
100 -33 -16 0 33 66
95 -21 -5 11 45 78
90 -10 6 23 56 90
85 1 18 35 68 101
80 13 30 46 80 113
75 25 41 58 91 125
70 36 53 70 103 136
65 48 65 81 115 148
60 60 76 93 126 160
55 71 88 105 138 171
50 83 100 116 150 183
45 95 111 128 161 195
40 106 123 140 173 206

Final Worth 25 Percent (1/4) Of The Course Score:

To Get
60 65 70 80 90
If You Have Requires
100 -60 -40 -20 20 60
95 -45 -25 -5 35 75
90 -30 -10 10 50 90
85 -15 5 25 65 105
80 0 20 40 80 120
75 15 35 55 95 135
70 30 50 70 110 150
65 45 65 85 125 165
60 60 80 100 140 180
55 75 95 115 155 195
50 90 110 130 170 210
45 105 125 145 185 225

Final Worth 20 Percent (1/5) Of The Course Score:

To Get
60 65 70 80 90
If You Have Requires
100 -100 -75 -50 0 50
95 -80 -55 -30 20 70
90 -60 -35 -10 40 90
85 -40 -15 10 60 110
80 -20 5 30 80 130
75 0 25 50 100 150
70 20 45 70 120 170
65 40 65 90 140 190
60 60 85 110 160 210
55 80 105 130 180 230
50 100 125 150 200 250
45 120 145 170 220 270
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4 thoughts on “What Do I Need To Get An A In This Class?

  1. Pingback: nebusresearch | What Do I Need If The Final Is Worth 40 Percent?

  2. Pingback: nebusresearch | December 2013′s Statistics

  3. Pingback: nebusresearch | The Math Blog Statistics, March 2014

  4. Reblogged this on nebusresearch and commented:

    And this post makes matters a little bit simpler, by showing charts of what minimum scores one needs on the final to get various minimum scores, for different final exam weightings. And, yes, if you’re going into a final exam with a high enough average, it’s conceivable that you could pass, or even get a better-than-passing, score with a zero on the final. Don’t do that. It makes your instructor sad. Just be less tense about the final instead.

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