Let old fashioned donuts = o and jelly donuts = j
Cost of o = $0.75
Cost of j = $1.20


Target question => How many jelly donuts did Andres buy?


Statement 1 => Andres bought a total of eight donuts
i.e o + j = 8; value of o and j is unknown. There are lots of variations that could satisfy the statement but will not provide a definite answer to the target question. Hence statement 1 is NOT SUFFICIENT.


Statement 2 => Andres spent exactly $7.35 on donuts since cost of o and j = $0.75 and $ 1.20 respectively
(0.75 * o) + (1.20 * j) = 7.35
0.75o + 1.20j = 7.35
(0.75o * 100) + (1.20j * 100) = (7.35 * 100)
75o/15 + 120j/15 = 7.35/15
50 + 8j = 49 .........eqn 1
By testing with numbers > or = 1, the only set of value that satisfies the equation above is when o = 5and j = 3
50 + 8j = (5 * 5) + (8 * 3)
=25 + 24 = 49


Statement 2 alone is SUFFICIENT
Answer = B

BTGmoderatorDC wrote: ↑

Mon Jul 13, 2020 7:16 pm

Andres bought exactly two sorts of donuts, old-fashioned donuts and jelly donuts. If each old-fashioned donut costs $0.75 and each jelly donut costs $1.20, how many jelly donuts did Andres buy?

(1) Andres bought a total of eight donuts.
(2) Andres spent exactly $7.35 on donuts.


OA B

Source: Magoosh

1) Andres bought a total of eight donuts.
\(O+J=8\). Not sufficient \(\Large{\color{red}\chi}\)

2) Andres spent exactly $7.35 on donuts.
\(0.75 \cdot O + 1.2 \cdot J = 7.35\)
\(75 O + 120 J = 735\)
\(5 O + 8 J = 49\)
\(O=5, J=3\) only one set of values satisfies this equation \(\Large{\color{green}\checkmark}\)

Therefore, B