Question

Sonam keeps a chart of how many kms she runs each day. If the pattern continues, how many days will Sonam take to run 6 kms.

Day	1	2	3	4
Distance (in kms)	$1\frac{1}{2}$	$1\frac{3}{4}$	$2$	$2\frac{1}{4}$

• A. 17 days
• B. 19 days
• C. 18 days
• D. 20 days

Answer 1

Answer: (B)

19 days

1st day - Sonam runs $1\frac{1}{2}=1.5$ kms.

2nd day - Sonam runs $1\frac{3}{4}=1.75$ kms.

Difference $=1.75-1.5=0.25$ km.

3rd day - Sonam runs $2$ kms.

Difference $=2-1.75=0.25$ km.

The difference remains constant with every passing day.

Hence, $d=0.25$, $a=1.5$ and $t_n=6$

And, $t_n=a+(n-1)d$

$\Rightarrow 6=1.5+(n-1)\times 0.25$

$\Rightarrow \frac{4.5}{0.25}=n-1$

$\Rightarrow 18=n-1$

$\Rightarrow n=19$

So, Sonam will take 19 days to run 6 km in one day.