A student investigated the temperature changes that occur when different salt samples are dissolved in water.
Their results are shown in the table below.
| Salt | Starting temperature of water in °C | Temperature of mixture after 3 minutes in °C | Temperature change in °C |
|---|---|---|---|
| P | 18.5 | 12.1 | -6.4 |
| Q | 18.5 | 24.2 | +5.7 |
| R | 18.5 | 11.2 |
Calculate the temperature change for salt R.
Include a sign/symbol in your answer to show if the temperature change is an increase (+) or a decrease (-).
