Question

please answer the question fast as possible and please don't give wrong answers​

Answer 1

Explanation:

This is the exact model of this question.

plzz substitute the values that you finds different from Akshara's question and solve .speed of boat =10km/h and speed of still water = 4km/h

Akshara i am in Sree Narayana School,chekkikkilam...kannur...kerala

Plz mark my answer as brainliest.

Nammal ore naattukaaralle....

Answer 2

Question:

A boat goes 30km upstream and 20km downstream in 7 hours. In 6 hrs , it can go 18 on upstream and 30 km downstream . Determine the speed of the stream and that of the boat in still water.

Answer:

Speed of boat = 8 km / hr

speed of stream = 2 km / he

Explanation:

Let the speed of boat be x km/hr.

Let the speed of stream be y km/hr.

Speed of upstream = x - y

Speed of downstream = x + y

According to the question :

$\implies \mathsf { \dfrac{30}{x - 1} + \dfrac{20}{x + y} } = 7$

$\implies \mathsf{ \dfrac{18}{x - y} + \dfrac{30}{x +1 } = 6}$

$\sf \longrightarrow \: let \: \frac{1}{x - y} \: be \: a \: and \: \frac{1}{x + y} be \: b.$

So,

$\sf \implies \: 30a + 20b = 7 \longrightarrow \: (1)$

$\sf \implies \: 18a + 30b = 6 \longrightarrow(2)$

Multiplying (1) by 3 and (2) by 5

So,

$\sf \implies \: 90a + 60ab = 21 \longrightarrow \: (3)$

$\sf \implies \: 90a + 150b = 30 \longrightarrow \: (4)$

On solving 3 and 4, we get.

$\sf \: \implies - 90b = - 9$

$\sf \: \implies \: .°. \: b = \frac{9}{90} = \frac{1}{10} = \frac{1}{x + y}$

Plugging the value in equation 3.

$\sf \implies \: 90a + 60b = 21$

$\sf \implies \: 90a + 60 \times \frac{1}{10} = 21$

$\sf \implies \: 90a + = 21 - 6$

$\sf \implies \: 90a + 60b = 15$

$\sf \implies \:a + = \frac{50}{90} = \frac{1}{6} = \frac{1}{x - y}$

so ,

x + y = 10

x - y = 6

$\sf \implies \: x = 8 \: km \: per \: hour$

$\sf \implies \: y = 2 \: km \: per \: hour$