Isolating a variable in the formula - practice problems
Work with mathematical expressions. Expressions are mathematical objects where some numbers are replaced by letters - variables. For example, the area of a circle is S = π r2, where r is a variable, the radius of the circle, and S is also a variable, the area. This is how we can describe the relationship between area and radius for all circles, generally. We can modify expressions, simplify, multiply, divide, add, etc. Expressing from a formula means putting some variable on the left side. For example, the radius of a circle r = √ (S/π). For completeness, let us add that the symbol π is a constant, Ludolf's number = 3.14159.... A constant is like a variable, but always with the same value.Number of problems found: 871
- A rope for cow
Find the length of a rope by which a cow must be tethered in order that it may be able to graze an area of 154 sq m . - The average 19
The average age of a class was 15 years. When 5 boys whose average age was 12 years 6 months were admitted in the class, the average was reduced by 6 months. How many students were there in the class originally? - Salaries - ratio3
The salaries A, B, C are in the ratio 2 : 3 : 5. If the increments of 15%, 10% and 20% are allowed respectively in their salaries, then what will be new ratio of their salaries? - Goods train
A goods train runs at the speed of 72 kmph and crosses a 250 m long platform in 26 seconds. What is the length of the goods train?
- Angle of inclination
Find the angle of inclination of a ramp that rise for 80 cm and is 200 cm long. - The length 20
The length and breadth of a rectangular park are in the ratio 8:5. A path,1.5 m wide, running all around the outside of the park has an area of 594 sq m. Find the dimensions of the park. - A field
A field is in the shape of a trapezium whose parallel sides are 25 m and 10 m and the non parallel sides are 14 m and 13 m. Find the area of the field. - The average 17
The average monthly salary of 20 workers in an office is $4590 . If the manage's salary is added, the average salary becomes $ 4920 per month What's the manager's monthly salary? - Four numbers 3
What least number must be added to each of the numbers 6,15,20 and 43 to make them proportional?
- Triangle 90
Triangle made by 6 cm 4.5 cm and 7.5 cm. what angles does it make? - 765 chairs
765 chairs are arranged in rows in such a way that the number of chairs in each row is equal to the number of rows. How many chairs needs to be removed to complete this arrangement? - Susan 5
Susan has a water tank in his back garden that can hold up to 750L in water. At the start of a rainy day (at 0:00) there is 165L in the tank, and after a heavy day’s rain (at 24:00) there is 201 L in the tank. Assuming that the rain fell consistently duri - The boat
A boatman goes 2 km against the stream in 40 minutes and returns to the same spot in 30 minutes. What is his rate of rowing in still water? - A plane 3
A plane left 30 minutes later than the scheduled time and in order to reach the destination 1500 km away in time, it has to increase the speed by 250 km/hr from the usual speed. Find its usual speed.
- Three inscribed objects
A circle is inscribed in a square. An equilateral triangle of side 4√3 is inscribed in that circle. Find the length of the diagonal of the square. - A long train
A train passes a standing man in 6 sec and 210 m long platform in 16 s . Find the length and the speed of the train. - Antecedent and consequent
In a ratio which is equal to 5:8, if the antecedent is 40, then find the consequent. - Two circles 3
Two circles are inscribed in a square whose side is 4 cm. Find the radius of the smaller circle. - Common work
39 men can repair a road in 12 days working 5 hours a day. How many days will be required to complete the work by 30 men working 6 hours a day?
A 110 m long train crosses a tree in 3 s. How long will it take to cross a 165 m long platform and 135 m long bridge, If the platform and bridge are at a distance of 30 m?Do you have unsolved problem that you need help? Ask a question, and we will try to solve it. Solving math problems.
