Intelligence Quotient (IQ) and Reasoning

(b) 24

Work is constant, so workers and days are inversely proportional: $18 \times 20 = x \times 15$, giving $x = \dfrac{360}{15} = 24$ workers.

(b) Rs. 1,800

Simple interest $= \frac{P \times T \times R}{100} = \frac{5000 \times 3 \times 12}{100} = \text{Rs. } 1{,}800$.

(b) 20
Total parts $= 7+5 = 12$. Each part $= 48 \div 12 = 4$, so girls $= 5 \times 4 = 20$.

(c) 10.5 years

Total age of 15 boys $=15\times 11=165$ years.
Total age of 5 new boys $=5\times 9=45$ years.
Total boys $=20$, total age $=165+45=210$ years.
Average $=\frac{210}{20}=10.5$ years.

(b) 16.66%

Discount = Rs. 2,400 − Rs. 2,000 = Rs. 400
Discount percent = $\frac{400}{2400}\times 100 = 16.66\%$