The GCSE Maths Tutor Flashcards
The mobile phone is reduced by 20% in a sale.
The sale price is £500.
Work out the original price of the mobile.
The mobile phone is reduced by 20% in a sale.
The sale price is £500.
Work out the original price of the mobile.
80% of 500
500 ÷ 80 = 6.25 which is 1%
£6.25 x 100 = £625
A house rises in value by 3%.
The value of the house increases by £7500.
Work out the value before the increase.
A house rises in value by 3%.
The value of the house increases by £7500.
Work out the value before the increase.
Need to find 100% + 3%
£7500 ÷ 3 = £2500 which is 1%
£2500 x 100% = 250 000
Emily invests £150 000 in a savings account offering a compound interest of 2.4% per annum for 4 years.
Work out the amount of interest she earns over 4 years.
Emily invests £150 000 in a savings account offering a compound interest of 2.4% per annum for 4 years.
Work out the amount of interest she earns over 4 years.
150 000 x 1.024^4
=164 926.74 - 150 000
=£14 926.74
Mary buys a car for £4000.
Each year it depreciates by 20%.
Work out the value of the car in 3 years.
Mary buys a car for £4000.
Each year it depreciates by 20%.
Work out the value of the car in 3 years.
Year 1 is £4000
20% = £800
4000 - 800 = £3200
Year 2 is £3200
10% = 320
20% = £640
3200 - 640 = £2560
Year 3 is £2560
10% = 256
20% = £512
2560 - 512 = £2048
In a bike store there are 8 different bikes and 10 different paint choices.
How many cominations are there?
In a bike store there are 8 different bikes and 10 different paint choices.
How many cominations are there?
8 x 10 = 80 combinations
A three digit padlock uses the numbers from 0 - 9.
How many of the possible three digit number combinations use three different digits?
A three digit padlock uses the numbers from 0 - 9.
How many of the possible three digit number combinations use three different digits?
10 x 9 x 8 = 720
6.4 has been truncated to one decimal place.
Write the error interval.
6.4 has been truncated (cut off) to one decimal place.
Write the error interval.
(Can’t write symbols so I’ve written the answer in words)
6.4 is lesser or equal to x which is lesser than 6.5
3 calculators and 4 books cost £23.
2 calculators and 3 books cost £16.
Work out the price of a single calculator and a single book.
3c + 4b = 23 x3 9c + 12b = 69
2c + 3b = 16 x4 8c + 12b = 64
c = 5
2(5) + 3b = 16
10 + 3b = 16
-10 -10
3b = 6
÷3 ÷3
b = 2
so c = 5 and b = 2
Find an expression in terms of n for the sequence 3, 5, 11, 15, 19
Hence the 50th term.
4n - 1
=4(50) - 1
=199
Find an expression in terms of n for the sequence 6, 11, 16, 21,26
Will 84 be in the sequence? Explain answer.
No, because the numbers all end in 6 or 1.
or
5n+1 = 84
-1 -1
5n = 83
÷5 ÷5
n = 16.6
So, no as it’s not a whole number.
Here are the equations of three straight lines.
Line 1: 2y = 6x +5
Line 2: y + 3x = 5
Line 3: 3x - y = 5
Two of these lines are parallel. Explain which two.
Need to turn each equation into the form y = mx + c
Line 1: 2y = 6x +5 is y = 3x + 2.5
Line 2: y + 3x = 5 is y = -3 + 5
Line 3: 3x - y = 5 is y = 3x + 5
(for line 3, to get rid of the -y, have to add y to both sides)
So, lines 1 and 3 both have a gradient of 3 so they are parallel.
Emily and James share some money in the ration 4:7.
James receives £21 more than Emily.
How much do they share between them?
E : J
4 : 7
There are 3 parts between them so 3 parts is £21.
21 ÷ 3 = £7
7 x 4 = 28
7 x 7 = 49
E : J
28 : 49 28 + 49 = £77
They share £77 between them.
A car has to travel 30 miles along a motorway in 24 minutes. Will the car have to travel faster than 70 mph to get there in 24 minutes?
70 miles = 60 minutes
÷ 10 ÷10
7 miles = 6 minutes
x4 x4
28 miles = 24 minutes
No.
6 taps take 3 hours to fill a tank with water. How long will it take 9 taps to fill the same tank?
State any assumptions you have made.
1 tap = 3x6 = 18 hours
18 ÷ 9 = 2 hours
*assuming all the taps are running at the same rate.
