DDA 2020 Exam Important Maths Questions with Answers: For clearing the DDA 2020 Exam, candidates must practice the most frequently appearing questions of different sections of the exam. Questions from the Arithmetical and Numerical Abilities Section will be asked in DDA 2020 Exam which will be conducted in online mode from 5th November Onwards. Numerical Ability/Quantitative Aptitude/ Mathematics Section will be part of the exam for various posts like Deputy Director, Assistant Director, Assistant Accounts Officer, Planning Assistant, SO (Horticulture), Architectural Assistant, Surveyor, Patwari, Junior Secretariat Assistant, Sr. Law Officer & Legal Assistant.
DDA 2020 Exam: Numerical Ability/ Quantitative Aptitude/ Mathematics Section
The test of Arithmetical and Numerical Abilities will cover Number Systems including questions on Simplification, Decimals, Fractions, L.C.M., H.C.F., Ratio & Proportion, Percentage, Average, Profit & Loss, Discount, Simple & Compound Interest, Menstruation, Time & Work, Time & Distance, Tables & Graphs, etc., of 10th level. So, in this article we have compiled some important Numerical Ability Questions which will help in your DDA 2020 Exam Preparation.
DDA 2020 Exam: Important Numerical Ability Questions with Answers
RATIO AND PROPORTION
The ages of Anjali and Renu are in the ratio of 6:7 respectively. After 6 years, the ratio of their ages will be 15:17. What is the age of Renu? (In years)
Explanation: ((6x + 6))/((7x + 6)) = 15/17
If the length and breadth of a rectangle are changed by +20% and –10% respectively. What is the % change in the area of the rectangle?
- 8% decrease
- 12 % increase
- 8 % increase
- 4 % increase
Explanation: 1 * b = Area
1 * 1 = 1
After changes, 1.2 * 0.9 = 1.08
There is 8% increase in the area.
TIME AND WORK
A can complete a piece of work in 12 days. A and B together can complete the same piece of work in 8 days. In how many days can B alone complete the same piece of work?
Explanation: Required number of days = 1/8 - 1/12 = 24 days
The compound interest on Rs. 10000 at 20 % p.a. in 4 years is? (In Rs)
Explanation: Required Compound interest = 10000 × (1.2)4 - 10000
10000 × (2.0736 - 1) =Rs. 10,736
TIME AND SPEED
Shweta when increases her speed from 25 km/hr to 30 km/hr. She takes one hour less than the usual time to cover a certain distance. What is the distance usually covered by Shweta? (in km)
- 150 km
- 120 km
- 90 km
- 180 km
Explanation: 25 × t = 30 × (t-1) = Distance
Distance = 150 km
A and B have together three times what B and C have, while A, B, and C together have 150 rupees more than that of A. If B has five times that of C, then A has
Explanation: A + B + C = 150 + A
B + C = 150
Also B = 5C
Solving the equations we get
C = 25 and B = 125.
Also, A + B = 3 (B + C)
Substituting B and C we get
A = 325
PROFIT AND LOSS
A shopkeeper purchased a table marked at rupees 400 at a successive discount of 10% and 15% respectively. He spent Rs.14 on transportation and sold the table of Rs.400. Find his gain percent.
- No loss or gain
Explanation: M.P= 200
Discount = 10% and 15 %
CP = 400 x 0.90 x 0.85 + 14 = 320
% gain = 80 ÷320 x 100 = 25%
PROBLEM ON TRAINS
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:
- 1 : 3
- 3 : 2
- 3 : 4
- 3 : 5
Explanation: Let the speeds of the two trains be x m/sec and y m/sec respectively. Then, the length of the first train = 27x metres, and the length of the second train = 17y metres.
27x + 17y = 23x + 23y
4x = 6y
The sphere has the same curved surface as a cone of slant height 16 cm and base radius 4 cm. Find the radius in cm?
Explanation: Curved surface area of cone = Curved surface area of cone
4× pi × r2 = pi × 4 × 16
r = 4 cm
Directions for questions: Study the following graph and answer the following question:
If the total investment in Stock A and C is Rs 2750 Crores, what is the total investment made in Stock D and E?
- 77 Crores
- 154 Crores
- 1375 Crores
- 995 Crores
Explanation: Investments in other than Stock A and C= 100-64= 36%
Investments in Stock D and E = 18%
So, Amount Invested in Stock D and E= 18 × (2750/36) = 1375 Crores