# Exponential equation - examples

- Photocopier

A photocopier enlarges a picture in the ratio 7:4. How many times will a picture of size 6cm by 4cm be enlarged to fit on a 30cm by 20 cm page? - Sequence

Calculate what member of the sequence specified by ? has value 643. - Exp

If ?, then n is: - Demographics

The population grew in the city in 10 years from 14000 to 27500. What is the average annual percentage increase of population? - Compound interest

Calculate time when deposit in the bank with interest 2% p.a. doubles. - Lion or virgin

We toss coin, every throw fits lion or a virgin with equal probability 1/2. Determine how much at least we have to make throws that with probability 0.9 lion fell at least once. - Crystal

Crystal grows every month 2.9 promile of its mass. For how many months to grow a crystal from weight 310 g to 482 g? - 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 3

In geometric sequence is a_{6}= 77760; a_{7}= 466560; s_{n}=93310. Calculate the first item a_{1}, quotient q and n - number of members by their sum s_n. - Coordinate

Determine missing coordinate of the point M [x, 108] of the graph of the function f bv rule: y = 3^{x} - Log

if ?, what is b? - Insert into GP

Between numbers 5 and 640 insert as many numbers to form geometric progression so sum of the numbers you entered will be 630. How many numbers you must insert? - When will I be a millionaire?

Chris monthly send 150 euros to the bank, which he deposits bear interest of 2.1% p.a. Calculate how many months must Chris save to save 1000000 euros? Inflation, interest rate changes or bank failures ignore. - Car value

The car loses value 15% every year. Determine a time (in years) when the price will be halved. - Radioactivity

After 115 hours decreases the activity of a radioactive substance to 1/9 of the initial value. What is the half-life of the substance? - Exponential equation

Solve exponential equation (in real numbers): 12^{-x-10}=18 - To the cinema

Jane at 8 am got message that all 1093 school pupils will 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 all the children in. - Interest

What is the annual interest rate on your account if we put 12700 and after 148 days received 12982.6? - Exponential equation

In the set R solve the equation: ? - Sum-log

The sum of two numbers is 10, the sum of their logarithms (base 10) is 1.1. Determine these numbers.

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