Riddles
Go to...
Index
Translations
Pronunciation
Images
Computers
Geography
Languages
0 / 60 seg.
Mr. Jones has two children. The older child is a girl. What is the probability that both children are girls?
T
H
_
P
R
_
B
_
B
_
L
_
T
Y
_
S
0
.
5
.
T
H
_
P
_
S
S
_
B
_
L
_
T
_
_
S
_
R
_
(
G
_
R
L
,
G
_
R
L
)
_
N
D
(
G
_
R
L
,
B
_
Y
)
.
S
_
T
H
_
P
R
_
B
_
B
_
L
_
T
Y
T
H
_
T
B
_
T
H
C
H
_
L
D
R
_
N
_
R
_
G
_
R
L
S
_
S
1
/
2
_
R
0
.
5
Clue
THE PROBABILITY IS 0.5. THE POSSIBILITIES ARE (GIRL, GIRL) AND (GIRL, BOY). SO THE PROBABILITY THAT BOTH CHILDREN ARE GIRLS IS 1/2 OR 0.5
TERRY IS 5 YEARS OLD. LET'S TRANSLATE WORDS TO MATH. "ALICE WAS FIVE YEARS OLDER THAN TERRY IS NOW" TRANSLATES TO: A = 5 + T, WHERE A IS THE AGE OF ALICE AND T IS THE AGE OF TERRY. NOW TRANSLATE AGAIN. "TERRY IS HALF AS OLD AS ALICE WAS" BECOMES : T = (1⁄2)A. SOLVING THE TWO EQUATIONS WILL GIVE T = 5
THE PROBABILITY IS 1/2. THERE ARE INITIALLY 4 POSSIBILITIES: GIRL-GIRL, GIRL-BOY, BOY-GIRL AND BOY-BOY. SINCE THE OLDER CHILD IS A BOY, WE CAN RULE OUT THE GIRL-GIRL AND GIRL-BOY COMBINATIONS
THE KING GAVE THEM ALL FAKE SEEDS; HE CHOSE THE LITTLE GIRL WHO WAS HONEST AND DIDN'T SWITCH SEEDS
Text
Audio
Text & audio
Free text
Multiple option
Previous question
Start
Next question
Please enable JavaScript to continue using this application.