21. If □ represents a digit in the 7-digit number 3, 62□, 215, what is the value of □?
(1) The sum of the 7 digits is equal to 4 times an integer.
(2) The missing digit is different from any of the other digits in the number.
Ans: C
我选E
(1)=>3+6+2+2+1+5+x=4K => 19+X=4K
(2)=>X=4,7,8,9，0
将（2）代入（1），得不出X=？ 所以我选E
我错在哪？
18. Bowls X and Y each contained exactly 2 jelly beans, each of which was either red or black. One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y. After the exchange, were both of the jelly beans in bowl X black?
(1) Before the exchange, bowl X contained 2 black jelly beans.
(2) After the exchange, bowl Y contained 1 jelly bean of each color.
Ans: E
我选D
each of which was either red or black.=>X，Y均是一红豆一黑豆？
22. Last Tuesday a trucker paid $155.76, including 10 percent state and federal taxes, for diesel fuel. What was the price per gallon for the fuel if the taxes are excluded?
(1) The trucker paid $0.118 per gallon in state and federal taxes on the fuel last Tuesday.
(2) The trucker purchased 120 gallons of the fuel last Tuesday.
Ans: D
