[JugglingReferee]

So a shooter tries a 3 and is fouled by 5 opponents simultaneously.

Missed:
0 points + possible 10 points [5 opponents * 2 shots/opponent] = 10 points maximum

Made:
3 points + possible 5 points [5 opponents * 1 shots/opponent] = 8 points maximum

Now, take into FTA% and 3FGA%. Most people shoot around 75% from the stripe. So, in case [missed], 0 + 10 * 0.75 = 7.5 points on average; and in [made], 3FGA% ~ 30% (agree?), which is 0.3* 3 + 5 * 0.75 = 0.9 + 3.75 = 4.65 points on average.

However, it comes down to a comparison between one's %ages.

Let x = % of FT
Let y = % of 3FG

[missed] 10x
[made] 5x + 3y

Break it down:
10x = 5x + 3y
5x = 3y
x = 3/5 y

if x > 3/5 y, then [missed] is better
if x < 3/5 y, then [made] is better
if x = 3/5 y, it is a wash

QED

Edit: change the formula in italics. My excuse was that I was trying to leave work...