ব্যাখ্যা
সমাধান:
Let,
P’s capital = p
Q’s capital = q
R’s capital = r
Then
4p = 6q = 10r
⇒ 2p = 3q = 5r
Here,
q = (2p)/3
r = (2p)/5
∴ P : Q : R = p : (2p)/3 : (2p)/5
= 15p : 10p : 6p
= 15 : 10 : 6
∴ Q will receive = 4650 × (10/31) = 150 × 10 = 1500
Bank Math Master · তারিখ অনির্ধারিত · ২১ প্রশ্ন
প্রশ্ন: Krishna invests Tk. 500 in the A Bank of Bangladesh at a simple interest rate of 8%. How much will be in his account after 5 years?
সমাধান:
Let,
P = Tk. 500
r = 8% = 8/100
n = 5 years
∴ I = Pnr
= 500 × 5 × (8/100)
= 200
∴ total amount after 5 years will be = (500 + 200)
= Tk. 700
প্রশ্ন: Haris and Sunny share some sweets in the ratio of 7 : 5. Haris has 12 more sweets than Sunny. How many sweets were there altogether?
সমাধান:
Let,
Haris has 7x sweets
Sunny has 5x sweets
∴ Total sweets 7x + 5x = 12x
ATQ,
7x - 5x = 12
⇒ 2x = 12
∴ x = 6
∴ There were 12 × 6 = 72 sweets altogether.
প্রশ্ন: A train is going at 1/3 of its usual speed and it takes an extra 30 minutes to reach its destination. Find its usual time to cover the same distance.
সমাধান:
Let,
The usual speed is x
The distance is d
The usual time is t min
So,
In usual speed, d = xt
In 1/3 of usual speed, d = (x/3) × (t + 30)
Now, We can say that,
xt = x(t + 30)/3
⇒ t = (t + 30)/3
⇒ 3t = t + 30
⇒ 2t = 30
∴ t = 15
∴ The usual time to cover the same distance is 15 min.
প্রশ্ন: Tk. 1500 is invested at 5% per year simple interest. In how many years the investment will be Tk. 1800?
সমাধান:
Here,
P = Tk. 1500
I = 1800 - 1500 = Tk. 300
r = 5% = 5/100
n = ?
We know that,
∴ I = Pnr
⇒ n = I/(Pr)
= (300 × 100)/(1500 × 5)
= 4
∴ The investment will be Tk. 1800 in 4 years.