Riddles
Go to...
Index
Translations
Pronunciation
Images
Computers
Geography
Languages
0 / 60 seg.
There are 12 kids in a classroom. 6 kids are wearing socks and 4 are wearing shoes. 3 kids are wearing both. How many are bare feet?
5
K
_
D
S
_
R
_
B
_
R
_
F
_
_
T
.
A
S
W
_
K
N
_
W
,
3
K
_
D
S
_
R
_
W
_
_
R
_
N
G
B
_
T
H
.
S
_
,
_
N
L
Y
3
K
_
D
S
_
R
_
W
_
_
R
_
N
G
_
N
L
Y
S
_
C
K
S
(
6
-
3
=
3
)
,
_
N
D
1
_
S
W
_
_
R
_
N
G
_
N
L
Y
S
H
_
_
S
(
4
-
3
=
1
)
.
S
_
,
_
N
T
_
T
_
L
,
3
+
3
+
1
=
7
.
N
_
W
,
1
2
K
_
D
S
_
R
_
T
H
_
R
_
,
S
_
,
1
2
-
7
=
5
Clue
THE NEXT NUMBER IN THE SEQUENCE IS 1113213211. EACH NUMBER DESCRIBES THE PREVIOUS NUMBER. STARTING WITH 1, THE SECOND NUMBER DESCRIBES IT AS 11 (ONE 1). THEN THE THIRD NUMBER DESCRIBES 11 AS 21 (TWO 1'S). THEN THE FOURTH NUMBER DESCRIBES 21 AS 1211 (ONE 2, ONE 1). TO DESCRIBE 13112221, IT HAS TO BE 1113213211 (ONE 1, ONE 3, TWO 1, THREE 2, ONE 1). IN MATHEMATICS, THIS IS CALLED THE LOOK-AND-SAY SEQUENCE
THERE ARE 9 SHEEP AND 18 CHICKENS. LET S BE THE NUMBER OF SHEEP AND C BE THE NUMBER OF CHICKENS. SO: 2S = C 5S + 3C = 99 WE CAN REPHRASE THE FIRST EQUATION, SO: 6S - 3C = 0 AND THEN WE CAN ADD THIS TO THE SECOND EQUATION, WHICH YIELDS: 11S = 99 BY SOLVING FOR S, WE FIND THAT S EQUALS 9. BY SUBSTITUTING BACK IN ONE OF THE ORIGINAL EQUATIONS, WE FIND THAT C EQUALS 18. SO THERE ARE NINE SHEEP AND EIGHTEEN CHICKENS
5 KIDS ARE BARE FEET. AS WE KNOW, 3 KIDS ARE WEARING BOTH. SO, ONLY 3 KIDS ARE WEARING ONLY SOCKS (6 - 3 = 3), AND 1 IS WEARING ONLY SHOES (4 - 3 = 1). SO, IN TOTAL, 3 + 3 + 1 = 7. NOW, 12 KIDS ARE THERE, SO, 12 - 7 = 5
THEY ARE 10.5 AND 0.5 YEARS OLD. A COMMON WRONG ANSWER IS 10 AND 1. THIS IS WRONG BECAUSE THE DIFFERENCE IN AGE WOULD BE 9, NOT 10
Text
Audio
Text & audio
Free text
Multiple option
Previous question
Start
Next question
Please enable JavaScript to continue using this application.