RRB NTPC Preparation Series: Part 1 - Percentages in Maths (Full Explanation)

 

RRB NTPC Preparation Series: Part 1 - Percentages in Maths (Full Explanation)

Friends! Ee RRB NTPC preparation series start chestunna, blog laa total parts ga divide chesi cheptha. Ee series lo CBT 1 & CBT 2 syllabus cover chestha – Maths, Reasoning, General Awareness. Start cheddam "Percentages" topic tho, enduku ante idi Maths lo high weightage undi (17-20% questions vastayi, as I mentioned earlier). Full neat explanation ivvabothunna, Telugu lo explain chestha but English typing lo (Romanized Telugu), easy ga artham avvali ani. English lo kuda key points ivvabothunna for clarity.

Idi Part 1: Percentages basics nundi advanced varaku, formulas, shortcuts, examples, NTPC previous questions. Tarwata parts lo Profit & Loss, Time & Work etc. Next part adugithe cheptha. Padu, notes teesko, practice chey! 💪

Introduction to Percentages (Telugu Explanation)

Friends, percentages ante emiti? Simple ga cheppalante, "percentage" ante "per cent" – adi 100 ki anta artham. Ee topic lo manam edo quantity ni 100 parts ga divide chesi calculate chestham. Ee topic NTPC lo important enduku ante, idi basic for many other topics like profit-loss, interest, data interpretation. CBT 1 lo 5-6 questions, CBT 2 lo 6-8 questions ravachu. Easy scoring if basics strong.

English: Percentages mean expressing a number as a fraction of 100. It's crucial in NTPC Maths as it appears directly and in related topics.

Basic Concepts & Formulas (With Telugu)

Percentage Formula (Basic): Telugu: Friends, edo number ni percentage ga marchali ante, adi (part / whole) * 100. 

Example: 20 apples lo 5 red unte, red apples percentage = (5 / 20) * 100 = 25%. English: Percentage = (Part / Whole) × 100.

1. Percentage to Fraction/Decimal: Telugu: 25% ante adi 25/100 = 1/4 fraction, or 0.25 decimal. Easy ga remember chey: % sign teesesi /100 chey. Example: 25% = 25/100 = 0.25 or 1/4.
2. Increase/Decrease Percentage: Telugu: Idi common question. Example: Salary 1000 nundi 1200 ayindi, increase percentage = [(new - old)/old] * 100 = (200/1000)*100 = 20%. Decrease kuda same, minus vastundi. English: % Increase = [(New Value - Old Value) / Old Value] × 100. Shortcut: If increase by x%, new value = old × (1 + x/100).
3. Successive Percentages: Telugu: Friends, two percentages vasthe, like 10% increase tarwata 20% decrease. Direct add/subtract cheyaku! Formula: Final % = x + y + (xy)/100. Example: 10% up + 20% down = 10 - 20 + (10(-20))/100 = -10 -2 = -12% (overall decrease). English: For two successive changes x% and y%: Effective % = x + y + (x*y)/100.
4. Percentage of Percentage: Telugu: 50% of 40% ante, first 40% calculate chey, tarwata dani 50%. But shortcut: (50/100) * (40/100) * whole. NTPC lo idi puzzles lo vastundi. English: A% of B% = (A/100) × (B/100) × 100% = (A*B)/100 %.

Shortcuts for NTPC (Time Saving Tricks)

Friends, exam lo time key, so shortcuts learn chey:

• 10% of any number = number / 10. (Ex: 10% of 500 = 50)
• 5% = half of 10% (Ex: 5% of 500 = 25)
• 25% = quarter (Ex: 25% of 400 = 100)
• 1% = number / 100. Telugu: Ee tricks daily practice chey, calculations fast avuthayi. Vedic maths laa, multiply cheyaku – divide chey.

English: Use these for quick calculations in MCQs.

Examples with Step-by-Step (NTPC Style)

Example 1 (Basic): Friends, question: 40% of 250 = ? Telugu: 40/100 * 250 = 0.4 * 250 = 100. English: Solution: (40/100) × 250 = 100.

Example 2 (Increase): Question: A number is increased by 25%, becomes 150. Original number? Telugu: Let original = x. x * (1 + 25/100) = 150 → x * 1.25 = 150 → x = 150 / 1.25 = 120. English: Original = 150 / (1 + 0.25) = 120.

Example 3 (Previous NTPC Type): Question: In an exam, 65% students passed in Maths, 75% in Science. If 10% failed in both, % passed in both? (Use inclusion) Telugu: Total passed = Maths + Science - both. But idi percentages lo Venn diagram laa. Passed in at least one = 65 + 75 - both. But failed both 10%, so passed at least one = 90%. So 65+75-both=90 → both=50%. English: % passed in both = 65 + 75 - 90 = 50%. (Since 100 - 10 = 90% passed at least one).

Practice Questions (Solve Chey, Answers End Lo)

1. 15% of 300 = ?
2. If price increases by 20%, then decreases by 20%, final % change?
3. 40 students lo 25% girls, girls number?

Answers: 1. 45, 2. -4% (20 - 20 + (20*-20)/100 = -4), 3. 10.

Tips for NTPC Percentages Preparation

• Telugu: Friends, daily 20-30 questions solve chey. Books: RS Aggarwal lo Percentages chapter padu. Online: Unacademy or Adda247 mocks teesko. Weak unte basics nundi start.
• English: Practice from previous years (2019-2024 papers). Focus on word problems like elections, marks, mixtures.
• Time: 1 week lo master chey, tarwata integrate with other topics.

Friends, idi Part 1 complete. Next part "Profit & Loss" meeda cheddam? Or ee topic lo doubts unte adugu.