Exponential equation - practice problems - page 7 of 8

Number of problems found: 144

The deposit
A deposit of € 2,612.5 was placed for one year at an annual rate of 4.5%. After one year, the amount rose to € 2,612.5. Find the initial deposit.
Price reduction
The price of the device is reduced by one-fifth every year. How long before the price of the device drops to one-tenth of the price? Specify years and months with precision.
The city 3
The city has 22,000 residents. How long is it expected to have 25,000 residents if the average annual population growth is 1.4%?
To the cinema
Jane at 8 AM got a message that all 1093 school pupils would go to the cinema. Within 20 min she said it to the three friends. Each of them again for 20 minutes said to the other three. In this way, the message spread further. At what time do all the scho
Car value
The car loses value by 15% every year. Determine a time (in years) when its price will halve.
Insert into GP
Between numbers 5 and 640, insert as many numbers as necessary to form a geometric progression, so the sum of the numbers you entered will be 630. How many numbers must you insert?
Half life
Determine the half-life of bismuth, when bismuth weight from the original weight of 32 g was only 2 grams in 242 minutes.
Geometric sequence
In the geometric sequence, is a₄ = 20 a₉ = -160. Calculate the first member a₁ and quotient q.
Lion or virgin
We toss the coin, and every throw fits a lion or a virgin with an equal probability of 1/2. Determine how much we have to make throws that, with the probability of 0.9, lions fell at least once.
Sum-log
The sum of two numbers is 19, and the sum of their logarithms (base 10) is 1.6. Determine these numbers.
Geometric sequence 3
In geometric sequence is a₄ = 40; a₉= 1280; s_n=2555. Calculate the first item a₁, quotient q, and n - number of members by their sum s_n.
Interest
What is the annual interest rate on your account if we put 43280 and after 198 days received 44293.9?
Exp
If sqrt[7](20²-12²) = sqrt[n](256), then n is:
Coordinate
Determine the unknown coordinate of the point M [x, 54] of the graph of the function f by rule: y = 3^x
Log
If log₄ x+ log₈ x = log_b x, what is b?
Crystal
The crystal grows every month at 1.2 permille of its mass. How many months does it take to develop from weight 177 g to 384 g?
Sequence
Calculate what member of the sequence specified by (5^n-2+15) has value 20.
Exponential equation
In the set R, solve the equation: 7^{-5 +19x}=4^{3 -20x}
Demographics
The population grew in the city in 10 years from 30000 to 34000. What is the average annual percentage increase in population?
Compound interest
Calculate the time it takes for a bank deposit earning 2.6% p.a. interest to double.

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