Practice: measures of centre, comparing and estimating
Practice: measures of centre, comparing and estimating
How many minutes Jonathan spent on homework each day, over 9 days:
Find the mode, the median and the range, and work out the mean.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
The number of rooms in 20 flats in a building:
| Rooms | 3 | 4 | 5 | 6 |
|---|---|---|---|---|
| Frequency | 5 | 8 | 5 | 2 |
Work out the mean number of rooms in a flat.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Find the mode, the median and the range.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
How the pupils of class 8D get to school:
Find the mode.
Can a mean or a median be worked out for these data? Explain.
The mean of five numbers is 12.
Four of them are 10, 15, 9 and 11.
Find the fifth number. Write an equation and solve it.
The mean of 8 numbers is 20.
The number 29 is added to them.
Work out the mean of the 9 numbers.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
The prices of six flats sold in one street, in thousands of shekels:
Work out the mean.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Find the median.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Which measure better describes the price of a typical flat in the street? Explain.
Two archers shot 6 arrows each. Their points:
- Lior:
- Yael:
Compare the archers by the mean, the median, the mode and the range.
Which of them is steadier? Which hits 10 more often?
The mean height of girls and of boys, by age, in cm:
| Age | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
|---|---|---|---|---|---|---|---|
| Girls | 138 | 144 | 151 | 157 | 160 | 162 | 163 |
| Boys | 139 | 143 | 149 | 156 | 163 | 170 | 174 |
- At which ages are the girls taller than the boys, on average?
- Estimate the mean height of girls at twelve and a half. What is such an estimate called?
- Can the boys’ line be carried on to estimate their height at 25? Explain.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Michal is saving money.
The points show how much money, in shekels, was in her money box at the start of each month (month 0 – when she started).
She forgot to write down the amount for month 2.
Write the formula of the trend: – the money in the box, – the number of months.
- How much money was in the box in month 2, by the trend?
- If the trend goes on, after how many months will there be 950 shekels in the box? Write an equation and solve it.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
A puppy’s weight, in kg:
| Age (months) | 2 | 4 | 6 |
|---|---|---|---|
| Weight (kg) | 2 | 6 | 10 |
- Estimate the puppy’s weight at 5 months.
- The puppy puts on 2 kg a month. By the trend, how much will the dog weigh at 3 years?
- Is the estimate of part 2 reliable? Explain.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power
Write four numbers whose mean is 10, whose median is 8 and whose range is 12.
Each of the data in a list is multiplied by 2.
What happens to the mean, the median and the range? Check it on the list , and explain.
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – check and a new line · * – times · ^ – power, ↓ – end of the power
/ – fraction bar · Tab or the arrows – between numerator and denominator, then a note above or below · Enter – a new line · * – times · ^ – power, ↓ – end of the power