Rational numbers - practice for 14 year olds - last page
Number of problems found: 55
- VAT
John paid 1000 Euros in store for purchase. Calculate value-added tax (VAT), which is paid in the purchase, if the VAT rate is 20%. - Discount
The ladies' sweater was twice discounted. First by 8%, then by 8% of the new price. Its final price was 66 €. Determine the original price of the sweater. - Pizza
A school survey found that 10 out of 15 students like pizza. If 5 students are chosen randomly, what is the probability that all 5 students like pizza? - Beer
After three 10° beers consumed in a short time, there is 5.6 g of alcohol in 6 kg adult human blood. How much is it per mille?
- Two doctors
Doctor A will determine the correct diagnosis with a probability of 89% and doctor B with a probability of 75%. Calculate the probability of proper diagnosis if both doctors diagnose the patient. - Madams
During the spring cleaning, ladies were going to wash the windows. Mother takes to wash all the windows 5 hours, the grandmother takes 3 times longer, and Paula washes all windows in 2 hours. How many hours will you spend washing the windows of this "wome - Sea water
Mixing 62 kg of seawater with 84 kg rainwater is created water containing 3.1% salt. How much percent of seawater contains salt? - Distribution 73724
The distribution of the random variable X is given in the following table. Calculate P[X is odd], E[X] and P[1<X≤6] Probability distribution table: xi; 1; 2; 3 ; 4; 5; 6; 7; 8; 9 pi; 0.30; 0.12; 0.18; 0.10; 0.07; 0.07; 0.06; 0.05; 0.05 - Pool
The swimming pool is 10 m wide and 8 m long, and 153 cm deep. How many hectoliters of water are in it if the water is 30 cm below its upper edge?
- Server
Calculate how many average minutes the web server is unavailable a year if the availability is 99.9%. - Scale
The swimming pool is long 110 m and 30 m wide. The city's plan is shown as a rectangle with an area 8.25 cm². What scale is the city plan? - Drinking water
A man drinks a keg of water in 36 days, and a woman drinks in 65 days. How many days do they consume a keg together? - Two cars
Two cars started against each other simultaneously to journey long 346 km. The first car went 53 km/h and the second 53 km/h. What distance will be between these cars 20 minutes before a meeting? - Pipes
The water pipe has a cross-section 1184 cm². An hour has passed 743 m³ of water. How much water flows through the pipe with cross-section 300 cm² per 6 hours if water flows at the same speed?
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