Blood Relations
🔒 Log in to trackCoded (symbol) relations
🔒 Log in to trackThe exam invents private symbols: 'P + Q means P is the father of Q'. Then a string like A + B x C hides a small family. Decode one symbol at a time into a plain sentence. Each symbol fixes the gender of its first letter only. Draw the tree, then answer in the question's direction.
What these questions look like
First come the definitions. Then a coded string, then a question about one pair in it.
Example: 'A + B' means A is the brother of B. 'A x B' means A is the wife of B. In the string A + B x C, how is A related to C?
No tree exists yet. You build it from the string, symbol by symbol.
Decode one symbol at a time
Cut the string at every symbol. Each cut gives one plain sentence:
- A + B: A is the brother of B.
- B x C: B is the wife of C.
Now draw. A and B share parents, so A sits beside B. B is married to C, so B and C share a row. Read the asked pair: A is the brother of C's wife, so A is C's brother-in-law.
Rule: One symbol = one sentence = one link on the tree. Never decode a whole string in one breath.
Track each letter's gender
This is the whole game. Every symbol fixes the gender of its first letter only:
| Symbol says | First letter becomes |
|---|---|
| father, son, brother, husband, uncle | male |
| mother, daughter, sister, wife, aunt | female |
| sibling, cousin, child, parent | no gender |
In A + B x C with the definitions above: A is male (from +), B is female (from x), C is not fixed by anything.
Watch: If the answer needs a gender nobody fixed, the right reply is the neutral word or 'Cannot be determined'. C, above, could be male or female.
The same symbol twice adds a generation
A + B + C, with + meaning 'father of', reads as: A is the father of B, and B is the father of C. So A is C's grandfather.
Each repeated parent symbol pushes one more generation. Mixed symbols mix a generation step with a sideways step: parent, then sibling, then spouse, and so on. Draw it. Do not try to feel the answer from the string.
Tip: Under the string, write the gender mark for every letter as you decode it: A + B x C becomes A(m) + B(f) x C(?).
Answer in the question's direction
Symbols read left to right. Questions read either way.
If A + B means 'A is the father of B', then 'How is A related to B?' is answered father, but 'How is B related to A?' needs B's gender. B was fixed only if some other symbol fixed it. Otherwise B is a child of A with no known gender: cannot be determined.
Watch: Most wrong answers here come from answering the string's direction instead of the question's.
Check your tree before marking
Two quick checks catch almost every slip:
- No person can be their own ancestor.
- Opposite genders for a marriage, where the symbol says husband or wife.
If either check fails, one symbol was decoded backwards. Find it before moving on.
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Two symbols, three letters
Two symbol definitions and a string like A + B x C. One pair's relation is asked.
Translate each symbol into one plain sentence.
Draw the mini tree: siblings share parents, couples share a row.
Read the asked pair, using only the genders the symbols fixed.
Two sentences already form one connected tree, and the answer is a single path on it.
'P + Q' means P is the brother of Q. 'P x Q' means P is the wife of Q. In 'A + B x C', how is A related to C?
Show solutionHide solution
A is B's brother, so A is male.
B is C's wife, so C is B's husband.
A is the brother of C's wife.
Brother-in-law
Three symbols, four letters
Three definitions and a string like A + B - C x D.
Decode left to right, one sentence per symbol, drawing as you go.
Each symbol adds one person. Spouses of parents are parents too.
Answer the asked pair. A gender no symbol fixed means a neutral word.
The string is just three small links. Three small links beat one long guess.
'P + Q' = P is the son of Q. 'P - Q' = P is the wife of Q. 'P x Q' = P is the brother of Q. In 'A + B - C x D', how is A related to D?
Show solutionHide solution
A is B's son, so A is male.
B is C's wife, so C is A's father.
C is D's brother, so D is A's aunt or uncle. A is D's sibling's son.
Nephew
Reverse ask on a coded string
The string runs A ... B ... C but the question asks how C relates to A.
Decode and draw exactly as usual. Do not reverse the string.
Take the viewpoint of the letter named after 'related to'.
Give the mirror word, and check which genders were fixed.
The tree has no direction. Only the final sentence must match the question's direction.
'X # Y' means X is the father of Y. 'X @ Y' means X is the sister of Y. In 'A # B @ C', how is C related to A?
Show solutionHide solution
A is B's father, and B is C's sister, so A is C's parent too.
Asked from A's side, going down one arrow.
C's gender: no symbol fixed it.
Son or daughter: cannot be determined
Build the string for a given relation
'Which expression means M is the maternal uncle of K?' The options are strings, not words.
Write the target as plain sentences, middle person included: M is the brother of K's mother.
Pick symbols that state exactly those sentences.
Check each option symbol by symbol. Reject any that changes a gender or a generation.
Each option claims one tree. The correct option must rebuild the target sentences exactly.
'P + Q' = P is the brother of Q. 'P - Q' = P is the mother of Q. Which expression means M is the maternal uncle of K?
Show solutionHide solution
Needed sentences: M is the brother of some L, and L is the mother of K.
M + L gives the brother sentence. L - K gives the mother sentence.
Joined: M + L - K.
M + L - K
Shortcuts that save time
For each symbol, write its one-line sentence under the string, then draw. Six symbols become three short sentences, and the drawing finishes the job.
'X % Y' = X is the wife of Y. 'X # Y' = X is the sister of Y. In 'M % N # O', how is M related to O?
Show solutionHide solution
M is the wife of N.
N is the sister of O.
M is married to O's sister.
Sister-in-law
Before marking, list every letter with the gender its symbols fixed. If the asked word needs a gender that stayed blank, the answer is the neutral word or 'Cannot be determined'.
'P @ Q' = P is the son of Q. 'P & Q' = P is the husband of Q. In 'P @ Q & R', how is R related to P?
Show solutionHide solution
P is Q's son.
Q is R's husband, so Q is male and R is his wife.
R is the wife of P's parent.
Mother
Mistakes to avoid
Where most students lose marks on this subtopic.
Decoding a whole string in one breath.
Cut at every symbol. One sentence per cut, then draw.
Fixing the gender of the second letter from the symbol.
'A is the brother of B' fixes A only. B stays blank until another symbol fixes it.
Answering the string's direction instead of the question's.
Read the question. If it asks the reverse pair, give the mirror word.
Forgetting the spouse of a parent is also a parent.
If B is C's wife and B is A's parent, then C is A's parent too.
Marking 'Cannot be determined' without checking every symbol.
List the gender marks first. Only a truly blank needed gender allows that answer.
Quick revision
Read this the night before the exam.
One symbol = one sentence = one tree link.
A symbol fixes the gender of its first letter only.
Parent of one sibling is parent of all the siblings.
Spouse of a parent is also a parent.
Same parent symbol twice = one more generation.
Answer the question's direction, not the string's.
A needed gender that stayed blank = 'Cannot be determined'.
Practice: 13 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 13 questions
Suggested time 10 min · wrong answers go to your mistake notebook automatically.