Mathematics
In a bacteria culture under observation in a laboratory, the population of 50 bacteria doubles itself every hour.
(1) Which of the following expressions gives the bacterial population after n hours ?
25n
50 x 2n
(2) The population size of the bacteria after 3 hours will be
- 200
- 300
- 400
- 500
(3) How many bacteria will be there in the culture after 1 day ?
50 x 224
50 x 212
(4) If the culture is observed after every one hour, find the number of hours after which the population size of the bacteria will be larger than 1000.
- 5
- 6
- 8
- 10
Exponents
2 Likes
Answer
(1) Given:
Initial Population = 50
Growth Rate = Doubles every hour (x2)
The population starts at 50 and multiplies by 2 for every hour.
General formula after n hours:
Population = 50 × 2n
Hence, option 3 is the correct option.
(2) Population size after 3 hours = ?
Population size after n hours = 50 × 2n [From step 1]
By replacing the value of 'n' with 3, we get:
Population size after 3 hours = 50 × 23 = 50 x 8 = 400
Hence, option 3 is the correct option.
(3) Bacteria in the culture after 1 day = ?
We know that 1 day has 24 hours
Population size after n hours = 50 × 2n [From step 1]
By replacing the value of 'n' with 24, we get:
Bacteria in the culture after 1 day = 50 × 224
Hence, option 2 is the correct option.
(4) After how many hours will the population be larger than 1000?
Let's test hours (n):
n = 4: 50 x 24 = 50 x 16 = 800
n = 5: 50 x 25 = 50 x 32 = 1600
Since 1600 > 1000, it happens at 5 hours.
Hence, option 1 is the correct option.
Answered By
2 Likes
Related Questions
State True or False :
(i) For any non-zero number a, we have (am)n = am+n.
(ii) If a and b are non-zero numbers, then
(iii) For a non-zero number x; (xm x xn) is equal to x to the power (m + n).
(iv) If a number p is multiplied n times, then the resulting number is pn.
(v) In an exponential notation xn; n is called the index.
A computer purchased for ₹72900 loses two-third of its value every year. Its value is evaluated at the end of every year.
(1) Which of the following expressions gives the value of the computer (in ₹) after n years?
(2) Find the value of the computer after 3 years.
- ₹8100
- ₹2430
- ₹5600
- ₹2700
(3) In how many years will the value of the computer be less than ₹200 ?
- 6 years
- 7 years
- 8 years
- 10 years
(4) By how much will the value of the computer reduce in 4 years ?
- ₹24300
- ₹1800
- ₹8100
- ₹72000
Assertion: can also be written as .
Reason: In xm, x is called the base and m is called the exponent.
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- Assertion (A) is true but Reason (R) is false.
- Assertion (A) is false but Reason (R) is true.
Assertion: xm ÷ ym = (x ÷ y)m
Reason: am x bm = (ab)m
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- Assertion (A) is true but Reason (R) is false.
- Assertion (A) is false but Reason (R) is true.