Standard Costing – Variances – Trying to calculate standard rate per labour hour

I’m a newcomer to your site and forum and I have started studying the ACCA F2 FMA.

Unfortunately, I’ve become stuck on a question which falls under Standard Costing- Variances. The question is as follows:

Car Company manufacturers & distributes brake discs to the car industry. The company operates integrated Standard Costing system where:

Purchases of materials are recorded at standard cost
Direct materials & labour costs are variable
Production overheads are fixed & absorbed using direct labour hours

Actual & Budgeted data for May is as follows:

Budgeted Direct Materials per unit – 2kg at £5 per kg
Direct labour – 0.5 hrs per unit
Budgeted production for the month – 10,000 units
22,500 kg of materials were purchased
Total standard cost of materials were £115,000
6000 direct labour hours were worked at £6 per hour
Budgeted Fixed production overheads were £240,000
Actual Fixed production overheads were £260,000

Variances for May were:
Material Price variance £11,250 Adverse
Labour efficiency variance £1,750 Adverse

Question:
Calculate the Actual number of brake discs produced?

My answer was as follows:
£115,000 / (2kg * £5) = £115,000 / £10 = 11,500 units

However, I have now become completely stuck on the following question and would be grateful for your assistance please.

Question:
Calculate the standard rate per labour hour ?

Thank you