If the number of cornmeal hotcakes sold by bakery B on Tuesday (that is, the…

Concept

In a table-based data-interpretation set the quantity being asked for is seldom printed; it has to be rebuilt from the printed columns using the identities supplied with the table. The governing identity here is: Total = Cornmeal + American + Swedish. Two standard tools do the rest: a rise of p percent multiplies a base quantity by (1 + p/100), and in a two-term ratio a : b a single known term fixes the other, because dividing the known term by its own ratio part gives the value of one part.

Applying it to Tuesday's sale at bakery B

1. Monday's row for bakery B prints the cornmeal figure directly: 280 hotcakes.

2. Tuesday's cornmeal count is 20 percent more than Monday's, so it is 280 x (1 + 20/100) = 280 x 1.2 = 336.

3. Tuesday's American count is supplied by the question itself: 320.

4. On Tuesday the American : Swedish ratio is 4 : 5, and the 320 American hotcakes correspond to the 4 parts, so one part = 320 / 4 = 80 and the Swedish count = 5 x 80 = 400.

5. Adding the three varieties gives Tuesday's total: 336 + 320 + 400 = 1056.

Cross-check

• Ratio test: 320 : 400 reduces by 80 to 4 : 5, exactly the ratio stated for Tuesday.

• Percentage test: 336 / 280 = 1.2, a rise of 20 percent over Monday's cornmeal count, as required.

• Row-consistency test: Monday's own row is internally sound, since the difference column gives American = 280 + 120 = 400 (the note makes American the larger of the pair) and therefore Swedish = 1080 - 280 - 400 = 400, which reproduces the printed Monday total of 1080. Monday's American and Swedish counts are not needed for Tuesday, because Tuesday supplies its own American count and its own ratio.

Total number of hotcakes sold by bakery B on Tuesday = 1056.