In a certain code language, ‘she is girl’ is coded as ‘7 3 9’; ‘he is boy’ is coded as ‘9 6 5’ and ‘girl is tall’ is coded as ‘9 3 8’. How is ‘she’ coded in that language?

Correct — D. Rule: a word shared by two statements takes the digit those two codes share.

'is' appears in all three statements and 9 appears in all three codes, so is = 9.

'she is girl' and 'girl is tall' share is and girl, and their codes share 9 and 3. Since is is already 9, girl = 3.

That leaves one word and one digit inside 'she is girl': she = 7, option (d).

Why the others are wrong

• (a)
  9 — 9 is the code for is, the word common to all three statements. It cannot also stand for she, which appears in only one of them.
• (b)
  8 — 8 appears only in the code for 'girl is tall', so it belongs to tall, the one word unique to that statement. She does not occur there at all.
• (c)
  3 — 3 is the code for girl, fixed by the overlap between 'she is girl' and 'girl is tall'. She is the word left over once is and girl are placed.

Sentence codes are solved by intersection, never by position. The digits are printed in an order that does not match the words, so nothing can be read off left to right.

Work from the most common word outwards. A word in every statement takes the digit in every code, a word in exactly two statements takes the digit in exactly those two codes, and the last word of a statement falls out by elimination.

Three statements here pin down is first, then girl, then she.

Key facts

• is = 9, because is and 9 both occur in all three statements.
• girl = 3, from the overlap of 'she is girl' with 'girl is tall'.
• she = 7, by elimination inside 'she is girl'.
• he and boy cannot be told apart from the data given.

Common traps

• Matching the first digit to the first word of the statement.
• Stopping at is = 9 and marking 9 as the answer.
• Assuming every word in the puzzle can be decoded, when two of them cannot.

No directly related past PYQ was found.