It's a long time since I saw a day where the cloudbase was as per the formula.
A couple from recent METARs with exactly that pair:
KCEF 291557Z 01010KT 7SM FEW012 21/07 A3025=
METAR UKLL 291500Z 25002MPS 220V290 9999 SCT040 21/07 Q1022 31090070 NOSIG=
or if you fancy an example in the other direction:
UAUU 291700Z 31003MPS CAVOK 09/07 Q1020 330///70 NOSIG RMK QFE749/0999=
EFUT 291650Z AUTO 08011KT CAVOK 13/12 Q1027=
It's absurd to set a question like that.
a) 560 feet
b) 56,000 feet
c) 5600 feet
is not unreasonable as a set of choices, but to give students the impression that a 14 point spread allows determination of the dewpoint to the nearest 1000 ft is just bad science.