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

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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

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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

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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