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when folded along the breadth
we have 2(l/2 +b) = 34 or l+2b = 34...........(1)
when folded along the length, we have 2(l+b/2)=38 or 2l+b =38.....(2)
from 1 &2 we get l=14 and b=10
Area of the paper = 14*10 = 140 sq cm

required area = [14 x 14 - (4 x 1/4 x 22/7 x 7 x 7) ]sq.cm

= 196 - 154 = 42 sq.cm.

required area = (area of an equilateral triangle of side 7 cm)- (3 * area of sector with à = 60 degrees and r = 3.5cm)
34*7*7-3*227*3.5*3.5*60360 sq cm

=34*49-11*0.5*3.5 sq cm

= 1.967 sq cm

perimeter of window = πr+2r 

= [(22/7) x (63/2) + 63] = 99+63 = 162 cm

let the radius of the pool be Rft

Radius of the pool including the wall = (R+4)ft

Area of the concrete wall = πR+42-R2=πR+4+RR+4-R = 8πR+2 sq feet

=> 8πR+2 = 1125πR2 =>11R2 =200R+2

Radius of the pool R = 20ft

let each wheel make x revolutions per sec. Then2π*72*x+2π*7*x*10=19802*227*72*x+2*227*72*x=198

 66x=198 

distance moved by smaller wheel in 3 revolutions 

=2*227*72*3=66cm 

speed of smaller wheel = 663 m/s = 22m/s

In this type of question, we will first calculate the distance covered in given time.

Distance covered will be : Number of revolutions x Circumference 

So we will be having distance and time, from which we can calculate the speed. 

Radius of wheel = 70 / 2 = 35 cm

Distance covered in 40 revolutions will be 40*circumferene=40*2πr=40*2*227*35=8800cm = 88 m

Distance covered in 1 sec  = 8810=8.8m/s=8.8*185km/hr=31.68km/hr

distance covered in 1 revolution = 2πr = 2 x (22/7) x 20 = 880/7 cm
required no of revolutions = 17600 x (7/880) = 140