২৮তম বিসিএস প্রিলিমিনারি টেস্ট/গণিত এর প্রশ্ন পরুন ।

প্রশ্নঃ If you count 1 to 100, how many 5s will you pass on the way?

বর্ণনাঃ From 1 to 100 there are 20 '5s' Those are 5, 15, 25, 35, 45, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 65,75,85, 95.

প্রশ্নঃ A farmer had 17 hens. All but 9 died. How many live hens were left?

বর্ণনাঃ This question's answer is given is the question. The second line says' all but 9 died' That means 9 hens live were left.

প্রশ্নঃ If two typist can type two pages in two minutes, how many typists will it take to type 18 pages in six minutes?

বর্ণনাঃ

2 pages can be typed in 2 minutes by 2 typists 
1 ''   "    "    "    " 1  "  " $\frac{2\times 2}{2}$ 
18 "   "    "    "    "  6 "  " $\frac{{\displaystyle 2\times 2\times 18}}{{\displaystyle 2\times 6}}$  

প্রশ্নঃ The fifth consonant from the beginning of this sentence is the letter ----

বর্ণনাঃ From the beginning of that sentence 1st letter is 'T' (consonant ), 2nd is 'h' (consonant), 3rd is 'e' (vowel), 4th is 'f' (consonant) 5th is 'i' (vowel), 6th is 'f' (consonant) and 7th is 't' (consonant). So the fifth consonant is 't'.

প্রশ্নঃ If the second day of the month is a Monday, the eighteenth day of the month is a ----

বর্ণনাঃ In the month 2nd day is Monday, then the 18 th day will be Wednesday. You can count down it in such way : 2nd day - Monday , 3rd -Tuesday, 4th -Wednesday, 5th -Thusday , 6th- Friday ,7th- Sat, 8th -Sun , 9th -Mon , 10th -Tues , 11th -Wed, 12 th -Thurs, 13th -Fri, 14 th-sat 15th -Sun, 16th -Mon , 17th -Tues , 18th-Wednesday.

প্রশ্নঃ Two men, starting at the same point, walk in opposite directions for 4 meters, turn left and walk another 3 meters. What is the distance between them?

বর্ণনাঃ In Right-angled triangle $$\begin{gathered} ∆OAD,OD=\sqrt{O{A}^2+A{D}^2} \\ =\sqrt{4^2+3^2}=5 miter \\ Similarly, for ∆OBC, OC=5 miter \\ .\text{'}. The dis\tan ce CD= 5 +5 =10 mitre \end{gathered}$$

প্রশ্নঃ 30% of 10 is 10% of which?

বর্ণনাঃ 30% of 10=10% of z $$\begin{gathered} \Rightarrow \frac{30}{100}\times 10=\frac{10}{100}\times z \\ \Rightarrow 3=\frac{z}{10} \\ .\text{'}. z=30 \end{gathered}$$

প্রশ্নঃ Rahim is 12 years old. He is three times older than Karim. What will be the age of Rahim when he is two times older than Karim?

বর্ণনাঃ

If karim's age is x, then Rahim's age will be 3x. 
According to question , 3x=12 
                    .'.   x=4 
after y years, Rahim's age will be doubled than Karim. 

প্রশ্নঃ Divide 30 by half and add 10. What do you get?

বর্ণনাঃ $30 ÷\frac{1}{2}+10 =30 \times 2 +10 =60 +10 =70$

প্রশ্নঃ If a man swims 4 miters upstream at 1 mph and back downstream to the same point at 4 mph, what is his average speed?

বর্ণনাঃ Let towards upstream he swims at v1 mph and towards downstream he swims at v2 mph . '. v1=1 and v2 = 4 Now, his average speed $$\begin{gathered} =\frac{2}{{\displaystyle \frac{1}{v_1}+\frac{1}{v_2}}}=\frac{2}{{\displaystyle \frac{1}{1}+\frac{1}{4}}} \\ =\frac{2}{{\displaystyle 1+\frac{1}{4}}}=\frac{2}{{\displaystyle \frac{5}{4}}}=\frac{2}{{\displaystyle \frac{5}{4}}}=2\times \frac{4}{3}=\frac{8}{5}=1.6 mph \\ [Rule of harmonic mean ] \\ Total 5 mph swims 8 mitres \\ 5\left|8\right| 1.6 mph \\ \frac{ 5}{{\displaystyle \frac{30}{{\displaystyle \frac{30}{\times }}}}} \end{gathered}$$