**Answer : (b)**

Explanation :let the price of the tape recorder be Rs.x and let there be n students in the group.

Then ,the contribution made by each student in two cases are Rs. x/n and x/n-2 respectively.

It is given that

Then

X= n

^{2}– 2n divided by 2

Now 170 ≤ x ≤ 195 , substitute x

340≤ n

^{2}– 2n ≤ 390

340+1 ≤ n

^{2}– 2n +1 ≤ 390+1

341 ≤ (n-1)

^{2 }≤ 391

19.4 ≤ n ≤ 20.7

N=20

Because n is a natural number

Price of the tape recorder (x) = n

^{2}– 2n / 2

X= (20)

^{2 }– 20 / 2

x= Rs.180

**Answer: ( c)**

Explanation : 3 men do the work in 1 day

8 women do the work in ¾ day

1 women will do the work in 3/4 * 8 = 6 days

Again, 18 children do the work in ½ day

1 child will do the work in ½ * 18 =9 days

A women does in 6 days = 1 work

1 women will do in 1 day = 1/6 work

3 women will do in 1 day = 1/6 * 3 = ½ work

1 child does in 9 boys = 1 work

1child will do in 1 day = 1/9 work

Work done by ( 3 women + 3 children) in 1 day = ½ + 1/3 = 5/6

Remaining work = 1-5/6 = 1/6

This part of work is to be completed by man.

1 man does 1 work in 3 days

1man will do 1/6 work in = 3/6 = ½ day

So 1 man should be employed for ½ day

**Answer: (d)**

Explanation: Rate of flow of water = 7m per sec = 700 cm per second

Length of water column in ½ hour = (700 * 30 * 60 )

Internal radius of circular pipe = 1cm

Obviously, water column forms a cylinder of radius 1cm and length = (700*30*60 ) cm

Volume of water that flows in tank in ½ hour = 22/7 * 1 * 1 * 700 * 30 * 60

V= πr

^{2}h

Let h cm be the rise in the level of water in the tank. Then,

Volume of water in the tank = 22/7 * 40 * 40 * h

Both volumes are equal

22/7 * 40 * 40 * h = 22/7 * 1 * 1 * 700 * 30 * 60

H= 787.5 cm ( rise in level )

**Answer : (b)**

Explanation:Let the cost price of the goods sold during the month be Rs. X

Marked price at 15% above cost price = 1.15x

Sale price after 5% discount = 0.95 * 1.15 x = 1.0925 x

Expenses= 6500

Profit during the month = 6% which can be equated as 1.0925 x – 1.06x = 6500

0.0325x = 6500

X= Rs. 200000

**Answer: (a)**

Explanation: If the car were not moving , the person would have heard the sounds at an interval of 12 minutes. Therefore ,the distance travelled by car in 11 minutes 40 seconds is equal to the distance that could have been covered by sound in 12min – 11min.40seconds = 20seconds

Distance covered by sound in 20 seconds = 330*20 = 6600 m

In 11minutes , 40seconds = 700 seconds that the car travels 6600 m

In 1sec the car will travel 6600/700 = 66/ 7 metre per second

Speed of the car = 66/7 * 18/5 km per hour

=1188/35

Speed of the car =

km per hour

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