General Aptitude - 1

• City A population is 68000, decreasing at a rate of 80 per year City B having population 42000 increasing at a rate of 120 per Year. In how many years both the cities will have same population ?
  Let this will take x years , now after x years both cities will have same population.
  so 68000-80x=42000+120x
  so 200x=26000
  so x=130 years
• A person buy the 6, 1 Rs stamps and 7, 50 paisa stamps he has given 12 Rs how much money he will get back ?
  6X1+7X0.50=9.50
  so 12-9.50=2.50 Rs he will get back
• In a company 3/5 of people know shorthand 1/4th know typing and 1/5 know both. What fraction of people do not know both?
  let x be total employees now 3x/5 know typing and 1x/4 know short hand and 1x/5 know both so employees who know either typing or short hand will be:
  3x/5 +1x/4 -1x/5 =13x/20
  so those who don't know both are:
  x-13x/20 =7x/20
  so 7/20 employees don't know both.
• There are 5 red shoes, 4 green shoes. If one draws randomly a shoe . What is the probability of getting red shoe ?
  probability of picking a shoe is 9c1 ie 9
  and probability of picking a red shoe is 5c1 ie 5
  so probability of picking a shoe and that is red will be 5/9
• If the sum of five consecutive numbers is 35. Find how many prime numbers are there ?
  Nos are 5,6,7,8 and 9
  so prime nos are 5 and 7
• If the length of the rectangle is reduced by 20% and breath is increased by 20 % what is the net change ?
  let l be length and b is breadth now area is lb
  new length is 0.8l and breadth is 1.2b so new area is 0.96lb
  so there will be a reduction in area by lb-0.96lb=0.04lb i.e. 4%