Q 5. Statistics
An Identity Card has the number ABCDEFG, not necessarily in that order, where each letter represents a distinct digit (1, 2, 4, 5, 7, 8, 9 only). The number is divisible by 9. After deleting the first digit from the right, the resulting number is divisible by 6. After deleting two digits from the right of original number, the resulting number is divisible by 5. After deleting three digits from the right of original number, the resulting number is divisible by 4. After deleting four digits from the right of original number, the resulting number is divisible by 3. After deleting five digits from the right of original number, the resulting number is divisible by 2. Which of the following is a possible value for the sum of the middle three digits of the number?
- The card number is ABCDEFG.
Case 1. It is given that number is divisible by 9 i.e. sum of the digits will be divisible by 9.
- Thus numbers can be 1+2+ 4+5+7+8+9= 36 which is divisible by 9
Case 2. Deleting two numbers from right number is divisible by 5 means last number is 5 or 0.
- Since there is no 0 among the digits as per 1st step, E=5.
Case 3. Deleting one number from right resulting number is divisible by 6 i.e. numbers which are divisible by both 2 and 3 are divisible by 6.
- This means, last digit of the given number is even and the sum of its digits is a multiple of 3.
- We have three even numbers (2, 4 and 8) and these should be at places of F, B and D in any order. No other digit would be even.
- Thus Possible value of CD are 12, 72 and 92.
- Now We have to find C + D + E.
- If CD = 12, C + D + E = 1 + 2 + 5 = 8,
- if CD = 72, C + D + E = 7 + 2 + 5 = 14,
- if CD = 92, C + D + E = 9 + 2 + 5 = 16.
- Only matched option is a.
Q 45. Statistics
Five friends P, Q, X, Y and Z purchased some notebooks. The relevant information is given below:
1. Z purchased 8 notebooks more than X did.
2. P and Q together purchased 21 notebooks.
3. Q purchased 5 notebooks less than P did.
4. X and Y together purchased 28 notebooks.
5. P purchased 5 notebooks more than X did.
If each notebook is priced 40, then what is the total cost of all the notebooks?
- As per question
1. Z = X + 8,
2. P + Q = 21,
3. Q = P – 5,
4. X + Y = 28,
5. P = X + 5.
- Solving 2 and 3 we get P = 13, Q = 8 (numbers of books purchased)
- Putting value of P in 5 we get X = 8
- This way we also find value of Y and Z from other equations as 20 and 16 respectively.
- So total number of books (P + Q + X + Y + Z) = 21 + 28 + 16 = 65.
- Each book cost 40, total cost = 65 × 40 = 2600.
Q 47. Statistics
A person X wants to distribute some pens among six children A, B, C, D, E and F. Suppose A gets twice the number of pens received by B, three times that of C, four times that of D, five times that of E and six times that of F. What is the minimum number of pens X should buy so that the number of pens each one gets is an even number?
- As per the question A = 2B, A = 3C, A = 4D, A = 5E and A = 6F.
- Thus B = A/2, C = A/3, D = A/4, E = A/5, F = A/6.
- Total number of pens: A + B + C + D + E + F = A + A/2 + A/3 + A/4 + A/5 + A/6 = 147A/60.
- Out of the given options, if we take 147A/60 = 294 i.e., A = 120,
- we get B = 60, C = 40, D = 30, E = 24 and F = 20 all even.
Q 54. Statistics
Let A, B and C represent distinct non-zero digits. Suppose x is the sum of all possible 3-digit numbers formed by A, B and C without repetition. Consider the following statements:
1. The 4-digit least value of x is 1332.
2. The 3-digit greatest value of x is 888.
Which of the above statements is/are correct?
- A, B and C are three distinct non-zero digits.
- Least such value would be possible for A, B and C as 1, 2 and 3.
- So, number formed would be 123, 132, 213, 231, 312, 321.
- Sum of these = 1332 .
- Thus, statement 1 is true.
- As the least number is in four-digit, a 3-digit number will not be possible.
- Hence, statement 2 is not true.
Q 8. Statistics
A biology class at high school predicted that a local population of animals will double in size every 12 years. The population at the beginning of the year 2021 was estimated to be 50 animals. If P represents the population after n years, then which one of the following equations represents the model of the class for the population?
- We can calculate the population of animals after 12 years. P = 50 × 2 = 50 × (2)1 = 50 × (2)^(12/ 12)
- After 24 years P = 50 × 2 × 2 = 50 × (2)^2 = 50 × (2)^(24/ 12).
- Thus, we can write the equation as P = 50 × (2)^(n/ 12).
- Thus, option (d) is correct answer.
Q 16. Statistics
A boy plays with a ball and he drops it from a height of 1.5 m. Every time the ball hits the ground, it bounces back to attain a height of 4/5th of the previous height. The ball does not bounce further if the previous height is less than 50 cm. What is the number of times the ball hits the ground before the ball stops bouncing?
To solve this problem, we need to determine how many times the ball hits the ground before it stops bouncing. The ball is initially dropped from a height of 1.5 meters and each time it bounces, it reaches 4/5th of the previous height. The ball stops bouncing when the height is less than 50 cm (0.5 meters).
Let's calculate the height after each bounce:
● First Bounce:
○ Initial height = 1.5 meters
○ Height after first bounce = \( \frac{4}{5} \times 1.5 = 1.2 \) meters
● Second Bounce:
○ Height after second bounce = \( \frac{4}{5} \times 1.2 = 0.96 \) meters
● Third Bounce:
○ Height after third bounce = \( \frac{4}{5} \times 0.96 = 0.768 \) meters
● Fourth Bounce:
○ Height after fourth bounce = \( \frac{4}{5} \times 0.768 = 0.6144 \) meters
● Fifth Bounce:
○ Height after fifth bounce = \( \frac{4}{5} \times 0.6144 = 0.49152 \) meters
After the fifth bounce, the height is approximately 0.49152 meters, which is less than 0.5 meters. Therefore, the ball will not bounce again after the fifth hit.
Thus, the ball hits the ground 5 times before it stops bouncing.
Q 58. Statistics
In an objective type test of 90 questions, 5 marks are allotted for every correct answer and 2 marks are deducted for every wrong answer. After attempting all the 90 questions, a student got a total of 387 marks. What is the number of incorrect responses?
- Let number of correct answered question = x
- Let number of wronged answered question = y
- As per the question. We get
- x + y = 90
- 5x - 2y = 387
- On solving above questions, we get x= 81 and y= 9
- Hence 9 questions are wrongly attempted.
Q 70. Statistics
As a result of 25% hike in the price of rice per kg, a person is able to purchase 6 kg less rice for ₹1,200. What was the original price of rice per kg?
As per question:
Expenditure = Rs. 1,200/-
Changes: Price increase of 25%, = 1200 × (125/100) = 1500/-
Person buys 6 kg less.
Suppose person buys x kg of rice at Rs. 1,200/-
Hike lead to reduce the quantity (x -6) kg.
Difference in both price is of 300/-
That means 6kg rice is of 300/-
⇒1 kg = 50/-
Rs. 50 is price after hike and orginal price is asked.
⇒ 125% = 50
⇒ 100% = 50 × (100/125) = 40
∴ Thus orignial price of rice per kg was Rs. 40/-.
Q 19. Statistics
Rakesh and Rajesh together bought 10 balls and 10 rackets. Rakesh spent 1300 and Rajesh spent 1500. If each racket costs three times a ball does, then what is the price of a racket?
• Let the cost of each ball is Rs. X. Then cost of each racket will be 3X.
• Cost of 10 balls = 10X, and cost of 10 rackets = 30X.
• So total cost = 10X + 30X = 40X.
• By the condition given in question, we have
• 40X = 1300 + 1500 or 40X = 2800 or X = 70. Price of each racket = Rs. 210.
Q 37. Statistics
If x is greater than or equal to 25 and y is less than or equal to 40, then which one of the following is always correct?
• Given that x is greater than or equal to 25. Also, y is less than or equal to 40.
• Let’s try to find the various values of y – x.
• If y = 40, x can take various values like 25, 26, 27,...
• In that case y – x will take values like 15, 14, 13, 12,......0, - 1 etc.
• If y = 39, x can take various values 25, 26, 27,...
• In that case y – x will take values like 14, 13, 12, 11 ..... 0, - 1 etc.
• Similarly, if y = 38, values of y – x will be 13, 12, 11, ..... 0, -1 etc. and so on.
• So, we can say that value of y – x is less than or equal to 15 in all cases.
Q 23. Statistics
If X is between -3 and 1, and Y is between -1 and 1, then X² - Y² is in between which of the following?
- Then If X is between -3, -1
- X2 is between 1 to 9
- If Y is between -1, 1
- Then Y2 is between 0, 1
- ⇒ X2 – Y2 is between 0, 9.
Q 12. Statistics
If there is a policy that 1/3rd of a population of community has migrated every year from one place to some other place, what is the leftover population of that community after the sixth year, if there is no further growth in the population during this period?
- One third of the population migrates every year. If initially the population was x, after the first year it will be x – x/3 = x (1 – 1/3) = 2x/3
- After second year, population = (2x/3) × (1 – 1/3) = (2/3)2 x
- Similarly, after sixth year, population = (2/3)6 x = (64/729)x, i.e. 64/729th part of the original population.
Q 41. Statistics
In a class, there are 18 very tall boys. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class?
- Let number of girls in the class be X
- Number of boys in the class will be 2X (2/3 being boys, total being X + 2X = 3X)
- Number of very tall boys = 3/4 * 2X = 18
- So X = 12.
Q 39. Statistics
A person has only ₹1 and ₹2 coins with her. If the total number of coins that she has is 50 and the amount of money with her is ₹75, then the number of ₹1 and ₹2 coins are, respectively
Let the Rs. 1 and Rs. 2 coins be x and y in number respectively. Given x + y = 50 and x + 2y = 75 Solving the above two equations, you get x = 25 and y = 25.