Prac Exam less/fewer

[fangtray]

When drive-ins were at the hiegh of their popularity in the late 1950s. some 4,000 existed in the US, but today there are less than one-quarter that many

a.
b. there are fewer than one-quarter as many
c. there are fewer than one-quarter of that amount
d. the number is less than one-quarter the amount
e. it is less than one-quarter of that amount.

what is the rule with fewer/ less here?

please help

[sam2304]

fewer than is used for countable nouns - Eliminate A/D/E
C - of that amount - what does amount refer to ? We are using numbers here so many is preferred.

IMO B.

[fangtray]

fewer than is used for countable nouns - Eliminate A/D/E
C - of that amount - what does amount refer to ? We are using numbers here so many is preferred.

IMO B.

doesn't that amount refer to 4,000? is it ambiguous?

[sam2304]

doesn't that amount refer to 4,000? is it ambiguous?

It is not ambiguous but its incorrect. Amount is right when we have uncountable objects. Here its number of drive ins and many is the logical one.