The answer given (wife gets 2/7, son gets 4/7, and daughter gets 1/7) would have the old man doing 3500 rpm in his grave.
Clearly he would never agree to his daughter getting only 1/4 what his son got.
The fair way would be to split the estate in half and divide each half per the original instructions.
Wife ends up with 1/2 of the total estate, son with 1/3, and daughter with 1/6.

I haven’t heard that episode yet, still on my podcast list, but I seem to recall this puzzler from several years before. Didn’t the will require the wife get twice what the daughter gets, and the son gets twice what the wife got?

Edit: Ok, I just listened to the relevant episode of Car Talk . I tend to agree w/ @insightful. There’s merit to Ray and Tom’s solution, mainly its simplicity. But @insightful 's seems more equitable given the ambiguous wording of the will.

Here’s a side by side comparison.

Ray & Tom’s solution vs insightful’s

wife: 2/7 vs 3/6
son: 4/7 vs 2/6
daughter: 1/7 vs 1/6

I got the answer Ray gave on the show. In the will, the decedent clearly states that his son should receive twice what his wife receives, and if he has a daughter, the wife should receive twice what the daughter gets. Whether that would be what the man would have decided ahead of time is irrelevant. Without language to clear it up, the only way you can fulfill both conditions of the will is to split it up 4/7, 2/7, and 1/7.