A three digit number consists of 9,5 and one more number .
When these digits are reversed and then subtracted from the original number the
answer yielded will be consisting of the same digits arranged yet in a different
order. What is the other digit?
Sol. Let the digit unknown be n.
The given number is then 900+50+n=950+n.
When reversed the new number is 100n+50+9=59+100n.
Subtracting these two numbers we get 891-99n.
The digit can be arranged in 3 ways or 6 ways.
We have already investigated 2 of these ways.
We can now try one of the remaining 4 ways. One of these is n 95
or 199n =796
the unknown digit is 4.
A farmer built a fence around his 17 cows,in a square shaped region.He used 27
fence poles on each side of the square. How many poles did he need altogether???
Sol. Here 25 poles Must be there on each side .And around four corners 4 poles
will be present. 4*25+4=100+4=104 poles.
On the first test of the semester, kiran scored a 60. On the
last test of the semester, kiran scored 75% By what percent did kiran's score
Sol. In first test kiran got 60
In last test he got 75.
% increase in test ( 60(x+100))/100=75
A group consists of equal number of men and women. Of them 10% of men and 45% of
women are unemployed. If a person is randomly selected from the group. Find the
probability for the selected person to be an employee.
Sol: Assume men=100,women=100 then employed men & women r (100-10)+(100-45)=145
So probability for the selected person to be an employee=145/200=29/40
Randy's chain of used car dealership sold 16,400 cars in 1998. If the chain sold
15,744 cars in 1999, by what percent did the number of cars sold decrease?
Sol. Let percentage of decrease is x , then
A radio when sold at a certain price gives a gain of 20%. What will be the gain
percent, if sold for thrice the price?
E) None of these
Sol. Let x be original cost of the radio.
The solding price = (100+20)x=120x
If , it is sold for thrice the price ,then 3*120x=360x
So, gain percent is (360-100)=260%.
If the Arithmetic mean is 34 and geometric mean is 16 then
what is greates number in that series of numbers?
Sol. Let two numbers be x, y;
Arthmetic mean=34=>( x+y)/2=34
geometric mean=16=>(xy)pow 1/2=16
By trail and error 16*16=64*4
So the greatest number int hat series is 64.
The diameter of the driving wheel of a bus is 140cm. How many revolutions per
minute must the wheel make in order to keep a speed of 66 kmph?
Sol. Distance to be covered in 1 min=(66*1000)/60 m=1100m
Circumference of the wheel =(2*22/7*0.70)m=4.4m.
So, Number of revolutions per min=1100/4.4=250.
The boys and girls in a college are in the ratio 3:2. If 20% of the boys and 25%
of the girls are adults, the percentage of students who are not adults is:??
Sol: Suppose boys = 3x and girls = 2x
Not adults = (80*3x/100) + (75*2x/100) = 39x/10
Required percentage = (39x/10)*(1/5x)*100 = 78%
Vivek travelled 1200km by air which formed 2/5 of his trip.One third of the
whole trip , he travelled by car and the rest of the journey he performed by
train. The distance travelled by tain was???
Sol: Let the total trip be x km.
Distance travelled by car =1/3*3000=1000km
Journey by train =[3000-(1200+1000)]=800km.
In a college ,1/5 th of the girls and 1/8 th of the boys took part in a social
camp.What of the total number of students in the college took part in the camp?
Sol: Out of 5 girls 1 took part in the camp
out of 8 boys 1 took part in the camp
so, out of 13 students 2 took part in the camp.
So, 2/13of the total strength took part in the camp.
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