Question

sove this please..........

Answer 1

(this pic is for 2nd )


1.
ANSWER:
5 km/hr

Explanation:

As the speed of the boat in still water is known to us we can calculate the speed of the stream either any stream i.e. down stream or up stream.
Say, the speed of the stream is x km/hr.
Going downstream the speed of the boat and the speed of the stream will be added together i. e. (35+x) km/hr
Hence the boat goes (35+x) km in 1 hr.
For a distance of 60 km, the Time =6035+xhr
so, 6035+x=112=32
or, 3(35+x)=2⋅60 [cross multiplication]
or, 105+3x=120
or 3x=120−105
or, x=153=5
Speed of the stream is 5 km/hr.
Another way
Going upstream, the speed of the stream is deducted from speed of the boat i.e (35−x) km/hr
Hence goes (35−x) km in 1 hr.
Therefore for a distance of 60 km Time = 6035−x hrs.
As per question, Time is 2 hours, so 6035−x=2
or 60=2(35−x) [ cross multiplication]
or, 60=70−2x
or 2x=70−60
or, x=102=5
So, speed of the stream is 5 km/hr.

Answer:

5 km/h

Explanation:

To solve this you only need one of the directions. That is; upstream or downstream. This is because you are given the speed of the boat in still water. Of you did not have the still water speed you would have to use both upstream and downstream.
Using ratio but in fraction FORMAT
For downstream we are given that:
distancetime→60km1.5h
But we need the distance in 1 hour (speed or velocity)
_______________

2. DIAGRAM IS IN PIC

In right triangle ABC, angle A= 90°

AB:AC=3:4

Therefore, AB=3x and AC=4x

By pythogorus theroum

BC=√AC×AC+AB×AB

BC=5x

Now, In rectangle BCDE , Length =BC=5x

Since, BC= 4/5×5x=4x

But,

Perimeter = 180cm

2×(5x+4x)=180

x=10

since, the shortest side of right ∆ ABC=3x
= 3×10
=30cm.