Exponentiation + percentages - math problems

If n is a positive integer and x is any real number, then x^n corresponds to repeated multiplication x^n=x×x×⋯×x (n times). We can call this “x raised to the power of n,” “x to the power of n,” or simply “x to the n.” Here, x is the base, and n is the exponent or the power.

Number of problems found: 27

Events
Event P has probability of 0.84. What is the probability that the event P occurs in 3, 5, 7 try.
Radioactive material
A radioactive material loses 10% of its mass each year. What proportion will be left there after n=6 years?
Unknown number x
5% from an unknown number equals the number 2⁶. What is the unknown number?
What is
What is the annual percentage increase in the city when the population has tripled in 20 years?
Investment
1000$ is invested at 10% compound interest. What factor is the capital multiplied by each year? How much will be there after n=12 years?
Medicine
We test medicine on 6 patients. For all drug doesn't work. If the drug success rate of 20%, what is the probability that medicine does not work?
Sale
If the product twice price cut by 25%, what percentage was price cut in total?
Deposit
If you deposit 719 euros the beginning of each year, how much money we have at 1.3% (compound) interest after 9 years?
JUDr. Usury
Judge JUDr. Usury approved the agreement on guilt and punishment where confessed to pay daily interest 0.18%. How big is a yearly interest? Year has 360 days.
Machine
Price of the new machine is € 62000. Every year is depreciated 15% of residual value. What will be the value of the machine after 3 years?
The city
At the end of 2010 the city had 248000 residents. The population increased by 2.5% each year. What is the population at the end of 2013?
Event probability
The probability of event P in 8 independent experiments is 0.33. What is the probability that the event P occurs in one experiment (chance is the same)?
Computer
The computer was purchased 10000,-. Each year, the price of a computer depreciates always the same percentage of the previous year. After four years, the value of the computer is reduced to 1300,- How many percent was depreciated price of the computer eac
Crystal
The crystal grows every month 1.2 permille of its mass. For how many months to grow a crystal from weight 177 g to 384 g?
Wire
One pull of wire is reduced its diameter by 14%. What will be diameter of wire with diameter 19 mm over 10 pulls?
All use computer
It is reported that 72% of working women use computers at work. Choose 3 women at random, find the probability that all 3 women use a computer in their jobs.
Family
What is the probability that a family with 7 childrens have: exactly 5 girls? 7 girls and 0 boys? Consider the birth probability of a girl is 48.69% and boy 51.31%.
Curiosity factor
A blogger starts a new website, initially the number of the traffic is 293 due to their curiosity factor. The business owner estimated that the traffic will increase by 2,6% per week. What will be the number of it in week 5?.
Mortage hypo loan
The Jonáš family decided to buy an older apartment, which cost EUR 30,000. They found EUR 17,000 and took the loan with the bank for the remaining amount. What interest did they receive if they repay this amount for 15 years at EUR 120 per month?
Before yesterday
He merchant adds a sale sign in his shop window to the showed pair of shoes in the morning: "Today by p% cheaper than yesterday. " After a while, however, he decided that the sign saying: "Today 62.5% cheaper than the day before yesterday". Determine the