Question

Taking sea level as zero, distance below sea surface as negative and distance above sea surface as positive, find the integers corresponding to the following situation:
A shark, swimming 40 m deep, sees a diver 20 m above him. The shark immediately rises 30 m to attack the diver, who dives deeper by 10 m. The positions of shark and diver are

• A. - 30 m and - 10 m respectively.
• B. - 10 m and - 30 m respectively.
• C. 30 m and 10 m respectively.
• D. 10 m and 30 m respectively.

Answer 1

The correct option is B - 10 m and - 30 m respectively.

The initial position of shark was - 40 m.
As the shark rises by 30 m, we add 30 to its initial position
$\Rightarrow$ - 40 + 30 = - 10 m

The initial position of diver was - 20 m.
The diver dives deeper by 10 m. So we subtract 10 from his initial position.
$\Rightarrow$ - 20 - 10 = - 30 m