Question

solve this plzz class 9​

Answer 1

We know Time=$\frac{Distance}{Speed}$

Distance=Speed×Time

Speed=$\frac{Distance}{Time}$

Let Distance =X km

Ship Sails To Island At Speed of =15 km/h

Time Taken=$\frac{x}{15}$

Sails Back To Starting Point at=10 km/h

Time Taken=$\frac{x}{10}$

$\boxed{\mathtt{Average\:Speed=\frac{Total\: Distance}{Total\:Time}}}$

He have Travel Distance 2 times .

Total Distance=2x

Total Time=$\frac{x}{15}+\frac{x}{10}$

=$\frac{2x+3x}{30}$ (LCM=30)

Total Time=$\frac{5x}{30}$

$\boxed{\mathtt{Average\:Speed= \frac{2 x}{ \frac{5x}{30} } }}$

$\boxed{\mathtt{Average\:Speed=\frac{2\cancel\:x}{5\cancel\:x}\times30}}$

$\boxed{\mathtt{Average\:Speed=\frac{2}{\cancel5}\times\cancel{30}}}$

$\boxed{\mathtt{Average\:Speed=2\times6}}$

$\boxed{\mathtt{\huge{Average\:Speed=12\:km/h}}}$