Question

(1) Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours. Find her
speed of rowing in still water and the speed of the current.
women and 5 men can together finish an embroidery work in 4 days, while 3​

Answer 1

Answer:

rithu is my friend's name

Step-by-step explanation:

who wrote this question

Answer 2

Answer

(i) Let her speed in still water be x and speed of stream be y

Now, According to question and using time =

speed

distance

⇒

x+y

20

=2 and

x−y

4

=2

⇒x+y=10;x−y=2

⇒On solving we get x=6andy=4

⇒speed of Ritu in still water is 6km/hr and that of a stream is 4km/hr.

(ii)

Let the one woman do x unit work in one day and man do y unit

Now according to question,

⇒2×x×4+5×y×4=1 (i)

⇒3×x×3+6×y×3=1 (ii)

⇒8x+20y=1;9x+18y=1

Multiply equation (i) by 9 and (ii) by 8 then we have

⇒72x+180y=9;72x+144y=8

On solving we have

⇒y=

36

1

that is one man can finish that work in 36days

⇒x=

18

1

that is one woman can finish that work in 18days

(iii)

Let the speed of bus bex and that of train be y

Now, according to question and using time =

speed

distance

⇒

y

60

+

x

240

=4⇒

y

15

+

x

60

=1 (i)

⇒

y

100

+

x

200

=

6

25

⇒

y

24

+

x

48

=1 (ii)

From (i)

⇒

x

1

=

60

1

(1−

y

15

) putting this in eq (ii)

⇒

y

24

+

60

48

(1−

y

15

)=1

⇒

y

24

+

5

4

−

y

12

=1

⇒∴y=60km/hr

then x=80km/hr